Check diamond

 

(57) Abstract:

To check whether caused by natural diamond layer of synthetic diamond it is irradiated with ultraviolet radiation of high energy to excite the emission of luminescence, commonly used to measure and compare the intensity of luminescence produced by the different zones of the diamond. In one embodiment, the use of the integrating shell and set the diamond on a rotating holder. The technical result - the simplification and acceleration of the method validation of the diamond. 2 C. and 18 h.p. f-crystals, 3 ill.

The invention relates to a method of checking printed on natural diamond layer of synthetic diamond and to the device to implement the method. This is especially important when testing whether a diamond is completely natural, or some part of it contains precipitated from the vapor phase of the diamond material, and it is detected.

Synthetic diamond material may be deposited on uncut or partially processed natural diamond, which is then treated, for example, in faceted on all sides of the diamond. Conversely, a coating of synthetic diamond material may be applied on fully formed the ü thin (it can be about 5-10 μm), however, the present invention can also be used for detection of thicker layers.

The value of the diamond depends in part on its weight. Therefore, synthetic diamond material can be applied over natural diamond jewelry before or after cut diamond to increase the weight of the final product.

However, the value of the diamond is determined by its authenticity and uniqueness, as well as the fact that it is completely natural (mined) diamond. Thus, the diamond, which was not increased by imposing a layer of synthetic diamond material is more expensive than diamond increased by using such a layer.

For many years developed a number of methods of synthesizing diamond material. One of these methods is the method of chemical vapor deposition (CVD), which uses the technology of low pressure, which consists in applying synthetic diamond (referred to in this description of "diamond CVD material from the gas to the substrate. Chemical deposition from the gas phase is the most likely method of applying a synthetic diamond on the diamond, although the proposed alternative technologies, such as physical deposition from the gas phase. And the logical diamond material, called in this description, a "doublet CVD/natural diamond.

Diamond CVD material can be applied not on the diamond and the diamond substrate. In the latter case, diamond CVD material can copy the structure of the diamond substrate (this is called "homoepitaxial growth"). Educated doublet CVD/natural diamond can be identical in appearance, density, and other typical physical properties fully natural stone, and identification of such a doublet CVD/natural diamond can be problematic.

The aim of the present invention is to provide a method of testing whether a diamond layer of synthetic diamond deposited on it, as well as a device to implement the method.

It is desirable that the device was simple and could be used relatively poorly prepared person. The method and apparatus should allow the use of their reliable and consistent jeweler practitioner who is not trained in the methods of laboratory analysis of jewelry. The method and the device should be suitable for testing a large number of stones manually and must be suitable for automation.

In GB 2275788 A disclosed method of determining whether a diamond layer synchronou or ultraviolet radiation of high energy and see the resulting pattern of luminescence for the detection of areas of applied synthetic diamond. Irradiated, preferably, the entire diamond, and the pattern is studied using a magnifying means or on the screen with the camera on the elements of the charge-coupled.

The portion of the subject invention, according to GB 2275788 And refers to checking whether a natural diamond layer applied thereto synthetic diamond. The diamond is irradiated, preferably, the cathode or the electron beam and the layer of synthetic diamond identify its special zone of growth, although it requires considerable skill.

In EP-A-0425426 A disclosed method for the identification of precious stones (including diamonds) to determine the differences of the precious stone and other precious stones. Thus, this method allows you to define the "fingerprint" of the precious stone. Gemstone lead to a state of luminescence and measure the level of luminescence on the set of pre-selected wavelengths.

In GB 2293236 A solved using an integrating sphere and ultraviolet radiation with a wavelength of 230-320 nm to test whether a natural diamond layer applied thereto synthetic diamond, and the diamond lies on a shelf made of quartz glass inside the integrating sphere and is irradiated black printed on natural diamond layer of synthetic diamond includes irradiating the diamond rays of high energy to excite the emission of luminescence diamond scan for the separate evaluation of the luminescence emitted by many different zones of the diamond surface, and determining whether there is substantial change in the luminescence from one zone to another, with the purpose of determining the presence deposited on the diamond layer of synthetic diamond.

The present invention also provides a device for determining the presence of applied natural diamond layer of synthetic diamond, comprising: a support for mounting diamond, means for irradiation of diamond fixed on the support, the radiation of high energy to excite the emission of luminescence diamond; scanning means for receiving separate signals dependent luminescence emitted by the set corresponding to different zones of the diamond surface; and means for indicating on the basis of these signals the diamond applied thereto a layer of synthetic diamond. If the means for the irradiation of irradiated diamond fixed beam, which is preferred, which may be less than diamond, so that is irradiated only part of the front surface of the diamond, the scan tool can oz. Scanning a stationary beam can be carried out by the means for driving or moving the support relative to the supports of the entire device while irradiating means are stationary with respect to the supports of the device.

The inventors have found that the search for significant differences in luminescence of different zones of the diamond is a particularly simple method for detection of surface layers of synthetic diamond material. There is no need for the image and the visual interpretation of complex images by the operator, as in GB 2275788 A.

Under the luminescence refers emitted radiation with a wavelength, in General, non-ionizing radiation that causes it.

Measure preferably the intensity of the luminescence. Create a preferable signal-dependent luminescence intensity of each zone. Alternatively, you can scan the surface of the diamond beam irradiating radiation, determining a significant change in luminescence intensity between one area and the next area.

The diamonds can be irradiated with ultraviolet radiation of a suitable wavelength. Basically all natural diamonds will be Lumi radiation with a wavelength of less than or approximately equal to 225 nm. Ionizing radiation can be mostly monochromatic or may contain a range or set of wavelengths.

It is preferable that was dominated by the irradiation of only the surface region of the diamond and its luminescence. This is because the layers of synthetic diamond can be relatively thin. When ionizing radiation penetrates to a depth substantially greater than the thickness of a thin layer of synthetic diamond material, it will be called luminescence below natural diamond material, which may distort or absorb the luminescence layer of synthetic diamond.

For this reason, it is preferable to irradiate the diamond radiation with a wavelength of less than or approximately equal to 225 nm, which is very strongly absorbed by all types of diamonds. This is described in more detail in GB 2275788 A.

Ionizing radiation may include radiation with wavelengths of more than 225 nm. Certain ranges of radiation with a wavelength of more than 225 nm have different absorption characteristics in different types of diamonds. In line with this, this radiation can penetrate through theoretically emitted from the layer and to cause luminescence in other areas of the diamond, which can distort the rising. It is desirable that such radiation with a wavelength of more than 225 nm must have a sufficiently low intensity so that the luminescence from diamond pieces, non-radiated areas, not cleaned or did not reduce the contrast of the observed luminescence.

Preferably, at least 50% of the energy of the radiation was in radiation with a wavelength of less than 225 nm. However, it is preferable that the radiation with a wavelength of more than 225 nm was excluded by using an appropriate filter.

As an alternative solution, the diamond can be irradiated by a beam of electrons of suitable energy, however, the device in this case becomes more difficult.

Irradiating the radiation must have an intensity sufficient to create luminescence sufficient for observation.

Ionizing radiation can be created using any suitable means, for example using a laser or other sources. Ionizing radiation can be directed to a gem by any suitable means. However, the attenuation of short wavelength ultraviolet radiation normal optics high, and it is preferable to use optical equipment, which is high the e 180 nm attenuated normal ultraviolet optics and oxygen in the air and effectively filtered by the device.

The radiation preferably focus on the diamond. It is preferable to focus the radiation on a certain area of the diamond, which is less than the total surface area of the diamond. Especially, it is preferable to focus the radiation to a small spot and scanned across the surface of the diamond.

As shown in more detail in GB 2275788 A radiation with a wavelength of less than 225 nm is absorbed mostly in the specified area of a surface of the diamond. This helps present invention that the luminescence observed upon irradiation of this zone will depend largely on the composition of the surface of the irradiated zone.

Ranges luminescence observed for different types of diamond (natural and synthetic), fall within a wide range of wavelengths, typically in the visible part of the spectrum. It is possible to form a signal-dependent luminescence intensity with relatively narrow or relatively wide range of wavelengths. In the latter case, it is preferable to provide a shut-off filter for excluding ionizing radiation.

A layer of synthetic diamond deposited on a natural diamond can be detected by luminescence from him has a different color than Cinzia from the natural parts of the diamond. Accordingly, when testing multiple zones of significant difference (for example, a weaker signal is about 80%, preferably 50% or less of the stronger) luminescence intensity generated by the different zones of the diamond suggests a doublet CVD/natural diamond. It is possible that the difference in the intensity of luminescence is not caused by the presence of a layer of synthetic diamond. The present invention specifies a useful direction. However, it may be useful to check further.

May be sufficient to check only a few areas (maybe only two) to detect differences in luminescence of different areas. But preferably check a large number of zones.

The radiation intensity in the method according to the invention can be assessed by eye. In this case, should be provided with means to prevent the potentially dangerous ultraviolet radiation on the observer. If the luminescence appreciate the eye, there is no need to create an image of the irradiated zone, if the irradiating radiation can limit the area of interest and to prevent exposure of other areas. In this case, consideration is subjected to ultimately luminescence, and is lsoe the number of incident radiation can be tolerated in the observed irradiation, if it doesn't blur the luminescence.

Fluorescent radiation can be detected using any suitable means. For example, in the path of the irradiating radiation, you can put the beam-splitter is made so that it directs the fluorescent radiation from the diamond to the detector. The detector can be equipped with a filter for filtering the irradiating radiation.

As an alternative solution, the diamond can be placed in the integral shell and to irradiate the area of the diamond of the irradiating radiation. Integrating the shell is provided with a detector to signal-dependent luminescence intensity in integrating the shell generated by the irradiation of this zone. Doctor may contain a filter for filtering the irradiating radiation.

Integrating the shell is preferably made in the form of a sphere.

When using an integrating shell must be irradiated are interested in the area of diamond and mostly not irradiated other areas.

Can be irradiated diamond using a beam of limited size that can be created using a diaphragm located between the diamond and the radiation source.

Preferably simultaneously irradiate one notesto different zones of the diamond at the same time and to create signals dependent luminescence intensity of each of the respective zones sequentially or simultaneously, and the results are compared sequentially. The diamond can be placed interest area in contact with the diaphragm to reduce the proportion of light from other parts of the diamond. This arrangement is particularly suitable when the location of the beam splitter in the path of the irradiation direction of the luminescence to the detector.

Limited beam may be variable or fixed size. Its size can match faces processed diamond or part of the face. Limited beam is preferably smaller than the maximum size of the diamond, or the size can be adjusted to achieve this. The aperture may have a transverse size of 1-15 mm, preferably 5-10 mm May be provided by iris, adjustable in size for best results.

It is preferable to focus the beam to a small spot size of 1 μm - 1 mm in diameter, preferably 5-100 μm, which is scanned preferably on the diamond.

Emitted by the diamond radiation may pass to the detector through the filter. The filter is preferably cut filter dlya selected ranges of luminescence. You can use, for example, several replacement filters, each of which transmits light with different wavelength.

The beam is preferably scanned (i.e., move continuously or semi-continuous) surface of diamond. Can be provided with means for scanning the beam in the form of means for moving the beam relative to the diamond. For example, you can rotate the diamond with respect to an axis that does not coincide with the beam of radiation. Preferably, the axis was perpendicular to the line of radiation. Can be provided with means for linear displacement of the diamond relative to the beam of radiation, for example, in two directions, perpendicular to the line of radiation.

Can be provided with means which generate a signal if the intensity emitted by the diamond radiation is changed by an amount exceeding a specified value. This is especially useful if a diamond is scanned continuously. This allows you to easily identify changes in the composition of the surface. For example, the means for issuing a signal may include means forming a signal depending on the intensity of radiation, and means generating a signal to signal changes, if the radiation intensity is changed to the specified spacebattle by more than 10%, preferably more than 20%.

Means for generating a signal may contain a timer, so that the signal change is generated only if the radiation intensity is changed by a specified amount within a specified period of time. Can be provided with means to change the length of time and/or value you want to change the signal before it is issued to signal changes.

In one embodiment, the diamond is placed on a rotating holder and rotate continuously and simultaneously measuring the intensity of luminescence. If noise or modulated DC signal (in this case the variation of luminescence intensity due to naturally occurring small local differences in the composition of the diamond and internal reflection and refraction) should be a much wider pulse higher or lower intensity, it can be assumed that there is a doublet CVD/natural diamond.

Diamond rotate preferably a large number of times to obtain a variety of results that can be statistically combined to obtain statistically superior results.

The invention uses predpochtite the e electron beam or ultraviolet radiation of high energy.

The device according to the invention is preferably made in a lightweight, sealed housing. This is necessary to prevent radiation from external sources to the detector and to prevent potentially harmful ultraviolet radiation of high energy and inducing damage to the skin and eyes.

The invention is illustrated in more detail by the example of execution drawings, which depict:

Fig. 1 is a schematic depiction of a device for carrying out the invention according to the first variant,

Fig. 2 is a schematic depiction of a device for carrying out the invention according to the second variant,

Fig. 3 - diagram of the received output signal.

Detailed description of the invention

In the device 1 shown in Fig. 1, diamond 2 is placed in or on the holder 3, which is made with possibility of rotation and which is transparent to short-wave ultraviolet radiation and visible light. The diamond is irradiated with ultraviolet radiation with a wavelength of less than 225 nm. The radiation generated by the source 4 (e.g., a xenon flash lamp, deuterium lamp or laser ultraviolet radiation). Irradiating the radiation filter shut-fil is irout on a small area of the diamond by means of a lens 6. In a small area of the diamond is called luminescence, the intensity and color of the excited luminescence depends on the local composition of the irradiated zone. Part of this luminescence is held back in the direction of irradiation to the separator 7 beam, which transmits the luminescence through the lens system 8 having a filter 9 for removing radiation with a wavelength of less than 225 nm, and the luminescence focus on the photomultiplier tube 10. Photomultiplier tube 10 is connected to the CPU 11 and the monitor 12 to display a signal, dependent on the generated luminescence.

In a preferred embodiment of the method according to the invention is exposed to many areas of the diamond by diamond fixing relatively rotatable holder 3 and the rotation of the holder (and diamond) relative to the rest of the device, so that the contact point of radiation is moved over the surface of the diamond. The holder is made also with the ability to move in the direction perpendicular to the beam and to the axis of rotation, so you can scan the full height by repeating the rotation.

Diamond 2 in Fig. 1 is a doublet CVD/natural diamond with a layer of synthetic diamond material CVD on the surface of the diamond is a noise signal, when ionizing radiation passes through a natural part of the stone, followed by a relatively wide cavity in the direction of lower (or higher) of the noise signal when the focused beam of the irradiating radiation is moved in the synthetic part of the stone, causing luminescence of different intensity.

The noise is caused by local variations in the composition of the diamond, external and internal reflection and refraction, etc.

The device according to Fig. 1 is not intended to detect color luminescence, although it can be modified for this purpose by adding multiple interchangeable colour filters in front of the detector.

Used in Fig. 1 optics is optics for UV radiation, which is produced, for example, Spindler and Hoyer.

In Fig. 2 schematically shows a device for the implementation of the second variant of the method according to the invention. In the device diamond 13, which represents a doublet CVD/natural diamond, mounted on a rotating holder similar to the holder 3 in Fig. 1. The holder and the diamond is placed inside the integrating sphere 15, which is covered with a material with good reflectivity in the visible range. Diamond allusory removes light with a wavelength of more than 225 nm, and is focused by lens 18 on the surface or near the surface of the diamond 13. Ionizing radiation has a wavelength less than 225 nm and therefore luminescence. A device for determining the flux density of light at the wavelength (wavelengths) luminescence is a photomultiplier tube 19. We have a filter 20 for filtering of incident radiation and the screen 21 in the integrating sphere 15 to ensure that the radiation falling on the photomultiplier tube 19, corresponds to the density of luminous flux in the field. Provided by the processor 22 and the monitor 23 to display the signal generated by photomultiplier 19.

Since diamond 13 is a doublet CVD/natural diamond, created a photomultiplier 19 signal during the rotation of the holder 14 and diamond 13 is similar to the signal displayed by the monitor of Fig. 1.

In Fig. 3 in more detail shows the signal generated by the photomultiplier 19 or 10, respectively, Fig. 2 or 1. Fluctuations of the signal (noise) caused by natural variations of the diamond are different from changes in the signal due to the presence of layers of synthetic diamond, the fact that fluctuations less in intensity and spread the 1 can be programmed to measure the rate of change of the signal, received c the photomultiplier tube 19 or 10. The processor 11 or 22 can be connected to a means for rotation, respectively, of the holder 3 or 14. Thus, it is possible to measure signal changes with respect to time or position of the holder 3 or 14. The processors 11 and 22 can be programmed to issue an alarm if the rate of change of the signal from the photomultiplier tube 10 or 19 exceeds a preset value. In this case, the signal is given, for example, on the monitor 12 or 23 to indicate a jump in the emission of the diamond. Such a leap in emissions can be correlated with the presence of a layer of synthetic diamond.

The present invention described above, only as examples, and possible modifications with respect to the inventive concept.

1. A way of checking on natural diamond applied thereto a layer of synthetic diamond comprising the irradiation of diamond radiation of high energy to excite the emission of luminescence diamond, characterized in that perform scanning for the separate determination of the luminescence emitted by the different zones of the diamond surface, determine the presence of significant changes in luminescence from one zone to another for measuring the ohms irradiation diamond beam, which is less than diamond, so that irradiate only the area of the front surface of the diamond by means of the relative movement of the diamond and the beam so that the beam successively irradiates different zones of the diamond.

2. The method according to p. 1, characterized in that the diamond is irradiated with radiation containing radiation with a wavelength of 225 nm.

3. The method according to one of paragraphs.1 or 2, characterized in that it forms the signal-dependent luminescence emitted by the respective different zones.

4. The method according to p. 3, characterized in that the signals depend on the intensity of luminescence.

5. The method according to one of paragraphs.3 or 4, characterized in that the automatically detect differences in individual luminescence signals and generate the indicator signal for the automatic classification of diamond like layer having applied thereto a layer of synthetic diamond, if the differences exceed the specified value.

6. The method according to p. 5, wherein the indicator signal is generated, if the intensity of the luminescence from one zone to another is changed by a specified amount within a specified period of time.

7. The method according to one of paragraphs.1-4, characterized in that the presence of substantial izmenenie stationary and move the diamond.

9. The method according to p. 1, characterized in that the beam is stationary and rotate the diamond.

10. The method according to one of paragraphs.1, 8 and 9, characterized in that the diamond is mounted inside the integrating shell.

11. The method according to one of the preceding paragraphs, characterized in that the diamond is irradiated by the beam forming a spot with a transverse size of 2-100 μm.

12. Device for checking deposited on the diamond layer of synthetic diamond, containing support for installing diamond tools for irradiation of a diamond mounted on a support, a radiation of high energy to excite the emission of luminescence diamond, characterized in that the device comprises a scanning means for providing the different signals, depending on the luminescence emitted by the set corresponding to different zones of the diamond surface, means for indicating on the basis of these signals the presence deposited on the diamond layer of synthetic diamond, and is provided for irradiating means for irradiating the diamond beam that is smaller than diamond so the exposure is subjected to only the area of the front surface of the diamond, and the scanning means provides relative movement of the diamond and the beam so that the beam posledovatelno for irradiation of diamond radiation, containing radiation with a wavelength of less than 225 nm.

14. Device according to one of paragraphs.12 or 13, characterized in that the signals depend on the intensity of luminescence.

15. Device according to one of paragraphs.12-14, characterized in that it contains means for automatic detection of differences in separate luminescence signals and for generating an indicator signal for the automatic classification of diamond having applied thereto a layer of synthetic diamond, if the difference exceeded the specified value.

16. The device according to p. 15, characterized in that the generating means generates the indicator signal if the intensity of the luminescence changes from one zone to another by a specified amount within a specified period of time.

17. The device according to p. 12, characterized in that is provided for irradiating means for irradiating the diamond fixed beam and means for moving the support.

18. The device according to p. 12, characterized in that is provided for irradiating means for irradiating the diamond fixed beam and means for rotating the support.

19. Device according to one of paragraphs.12, 17 and 18, characterized in that the bearing diamond is integrating the shell.


 

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