EP0041348A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A method of assessing the colour in diamonds and other gems
Assignee: De Beers Consolidated Mines Ltd
•
Filing: 1981-05-21
•
Granted: —
•
Expires: 2001-05-21
Abstract
Abstract A method of assessing the colour of a diamond or other gem is provided which comprises determining the proportion of diffuse light incident upon the gem which is transmitted by the gem as well as a device for use in this method:
Inventors
- 👤 Geoffrey Steward Woods
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 21:58
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/87
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
30 words
A method of assessing the colour of a diamond or other gem characterised by determining the proportion of diffuse light incident upon the gem which is transmitted by the gem.
Claim 2
Independent Claim
30 words
A method of assessing the colour of a diamond or other gem characterised by determining the proportion of diffuse light incident upon the gem which is transmitted by the gem.
Claim 3
Dependent Claim
55 words
A method according to claim 1 which comprises determining the proportion of diffuse light of a given single wavelength incident upon the gem which is transmitted by the gem, repeating this determination for different wavelengths of light over the visible wavelength range so as to obtain a transmission spectrum and calculating the chromaticity co-ordinates therefrom.
Claim 4
Dependent Claim
15 words
A method according to claim 1 or 2 in which the gem is a diamond.
Claim 5
Dependent Claim
15 words
A method according to claim 3 in which the gem is a brilliant cut diamond.
Claim 6
Independent Claim
89 words
A method according to any one of claims 1 to 4 in-which the gem is mounted in a device which comprises an integrating sphere provided with two opposed holes, one of said holes being adapted to receive a beam of light and the other adapted to receive a gem in light-proof manner, the interior of the sphere being coated to provide a substantially completely diffuse reflector at all wavelengths and being provided with a baffle situated so that light entering the sphere impinges upon it thereby to diffuse it.
Claim 7
Dependent Claim
70 words
A method according to claim 5 in which the said other hole is provided with a ring in which the specimen can be mounted, said ring being held in light-proof manner in the said other hole by a threaded collar which threadedly engages the walls of the hole, the ring being equipped with an upstanding annulus coated so as to diffuse light which impinges on it from within the sphere.
Claim 8
Dependent Claim
34 words
A method according to claim 5 or 6 in which the gem is mounted in a device as claimed in claim 6, the gem being secured to the ring with compressed barium sulphate powder.
Claim 9
Dependent Claim
49 words
A set of diamonds or other gems for use as a comparative standard for colour assessment, in which set the diamonds or other gems have been graded with reference to their chromaticity co-ordinates, said co-ordinates determined by a method as claimed in any one of claims 2 to 7.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.