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1. (WO2017001835) MESURES DE LUMINESCENCE DANS LE DIAMANT
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS:

1. A method of providing an indicator for a diamond as to whether it is natural by testing for the presence or absence of one or more specific markers in the luminescence properties of the diamond, said markers characterised by luminescence decay time and luminescence wavelength.

2. The method of claim 1 , further comprising:

irradiating the diamond with at least one excitation pulse of electromagnetic radiation;

during and/or following the excitation pulse, detecting light emitted by the diamond in at least one time window having a predetermined time relationship relative to the excitation pulse so as to obtain luminescence data, the or each time window being chosen to include luminescence having a decay time characteristic of one or more of the markers; and

analysing the luminescence data in order to establish the presence or absence of the one or more markers.

3. The method of claim 2, further comprising irradiating the diamond with multiple excitation pulses, and detecting light emitted by the diamond so as to obtain luminescence data from at least one time window associated with each excitation pulse, the or each time window being closed before the start of the next excitation pulse.

4. The method of claim 3, further comprising combining the luminescence data associated with all of the pulses.

5. The method of claim 4, wherein combining the luminescence data comprises averaging the luminescence data obtained in a specific time window associated with each excitation pulse over all of the pulses so as to produce an averaged image or spectrum for the light emitted in that time window.

6. The method of claim 4 or 5, comprising obtaining an image from the luminescence data for each time window associated with each excitation pulse, and wherein combining the luminescence data comprises displaying to a user the images from a specific time window for all of the pulses.

7. The method of claim 6, wherein the images are displayed to the user in the form of a video.

8. The method of any of claims 2 to 7, further comprising synchronising a source of the excitation pulses with a light detector.

9. The method of any of claims 2 to 8, further comprising opening a time window after the associated excitation pulse has ended, so that the luminescence data comprises phosphorescence data.

10. The method of any of claims 2 to 9, further comprising opening a time window at the same time or very shortly after the start of the associated excitation pulse and closing said time window before or at the same time as the associated pulse ends, so that the luminescence data comprises fluorescence data.

11 . The method of any preceding claim, wherein one of the one or more markers is a blue fast phosphorescence marker comprising luminescence in a wavelength band peaking at about 450 nm and a decay time of less than about 80 ms.

12. The method of claim 1 1 , wherein testing for the blue fast phosphorescence marker comprises testing, in a time window opening at or after the end of the excitation pulse and ending about 80 milliseconds after the end of the associated excitation pulse, for a luminescence band peaking at about 450 nm.

13. The method of claim 1 1 or 12, wherein the presence of the blue fast phosphorescence marker is an indicator that the diamond is a natural type Ma or la diamond.

14. The method of any preceding claim, wherein one of the one or more markers is a turquoise slow phosphorescence marker comprising luminescence having a wavelength peaking at about 480nm and a decay time greater than 80 milliseconds.

15. The method of claim 14, wherein testing for the turquoise slow phosphorescence marker comprises testing, in a time window opening about 80 milliseconds after the end of the associated excitation pulse, for a luminescence band centred around 480nm, the time window optionally closing about 500 ms after the end of the associated excitation pulse.

16. The method of claim 14 or 15, wherein the presence of the turquoise slow phosphorescence marker is an indicator that the diamond is a type lib diamond.

17. The method of any preceding claim, wherein one of the one or more markers is a green slow phosphorescence marker comprising luminescence having a wavelength between about 530nm and about 550nm and a decay time greater than 80 milliseconds.

18. The method of claim 17, wherein testing for the green slow phosphorescence marker comprises testing, in a time window opening about after the end of the associated excitation pulse, for a luminescence band between about 530nm and about 550nm, the time window optionally closing about 500 ms after the end of the associated excitation pulse.

19. The method of claim 17 or 18, wherein the presence of the green slow phosphorescence marker is an indicator that the diamond should be referred for further testing.

20. The method of any of claims 2 to 19, wherein one of the one or more markers is an absence marker comprising negligible luminescence after the excitation pulse has ended.

21 . The method of claim 20, wherein the presence of the absence marker is an indicator that the diamond should be referred for further testing.

22. The method of any preceding claim, wherein one of the one or more markers is an orange long lived fluorescence marker comprising luminescence having a wavelength between about 535 nm and about 600 nm and a decay time less than 1 millisecond.

23. The method of claim 22, wherein the presence of the orange long lived fluorescence marker is an indicator that the diamond should be referred for further testing.

24. The method of any preceding claim, wherein one of the one or more markers is a red phosphorescence marker comprising luminescence having a wavelength between about 575 nm and about 690 nm and a decay time greater than 1 millisecond.

25. The method of claim 24, wherein the presence of the red phosphorescence marker is an indicator that the diamond should be referred for further testing.

26. The method of any of claims 2 to 25, wherein one of the one or more markers is a weak green fluorescence marker having a wavelength of about 510nm.

27. The method of claim 26, wherein testing for the weak green fluorescence marker comprises testing in the time window synchronised with the excitation pulse.

28. The method of claim 26 or 27, wherein the presence of the weak green fluorescence marker is an indicator that the diamond should be referred for further testing.

29. The method of any of claims 2 to 28, wherein the electromagnetic radiation of the excitation pulses is in the ultra-violet spectrum, optionally having a wavelength of 225 nm or less.

30. An apparatus for providing an indicator as to whether a diamond is natural by measuring luminescence properties of the diamond, the apparatus comprising:

a source of electromagnetic radiation;

a light detection device for capturing visible light emitted by the diamond; and a control system configured:

to synchronise the source and light detection device;

to cause the source to irradiate the diamond with at least one excitation pulse of electromagnetic radiation; and

to cause the light detection device to capture visible light emitted by the diamond during at least one time window having a predetermined time relationship relative to the excitation pulse so as to obtain luminescence data; wherein the or each time window is chosen to encompass one or more specific markers in the luminescence properties of the diamond, said markers characterised by luminescence decay time and luminescence wavelength and providing an indicator of whether the diamond is natural.

31 . The apparatus of claim 30, wherein the control system is configured to cause the source to irradiate the diamond repeatedly with a series of excitation pulses, and wherein the at least one time window is associated with each excitation pulse and is configured to close before the start of a subsequent excitation pulse.

32. The apparatus of claim 30 or 31 , further comprising a processor to analyse the luminescence data associated with the or each pulse to determine whether a marker is present.

33. The apparatus of claim 31 or 32, wherein the processor is configured to combine luminescence data associated with all of the pulses.

34. The apparatus of claim 33, wherein the processor is configured to combine the luminescence data by averaging luminescence data acquired over many pulses.

35. The apparatus of any of claims 30 to 34, wherein the processor is configured to obtain an image from the luminescence data for each time window associated with each excitation pulse, the apparatus further comprising a display device for displaying the images to a user.

36. The apparatus of claim 35, wherein the display device is configured to display to a user the images from a specific time window for all of the pulses.

37. The apparatus of any of claims 30 to 36 and configured to measure phosphorescence in a diamond, wherein the control system configures the light detection device to capture visible light during a time window which opens after the associated excitation pulse has ended.

38. The apparatus of claim any of claims 30 to 37 and configured to measure fluorescence in a diamond, wherein the control system configures the light detection device to capture visible light during a time window which opens at the same time as the associated excitation pulse begins and which closes before or at the same time as the associated pulse ends.

39. The apparatus of any of claims 30 to 38, wherein the control system is configured to enable one or more of the following to be operator controllable: time window start time relative to excitation pulse start or excitation pulse end, length of time window, number of excitation pulses, frequency of excitation pulses.

40. The apparatus of any of claims 30 to 39, wherein the control system is configured to allow a user to trigger an excitation pulse.

41 . An apparatus as claimed in any one of claims 30 to 40, wherein the electromagnetic radiation of the excitation pulses is in the ultraviolet spectrum.