US 12,436,092 B1
Continuous line for automatic diamond color grading evaluation
Yuelin Wang, Hong Kong (HK); Ziqi Wang, Hong Kong (HK); and Chun Zhang, Hong Kong (HK)
Assigned to Hong Kong Applied Science and Technology Research Institute Company Limited, Hong Kong (HK)
Filed by Hong Kong Applied Science and Technology Research Institute Company Limited, Hong Kong (HK)
Filed on Oct. 10, 2024, as Appl. No. 18/911,583.
Int. Cl. G01N 21/25 (2006.01); B07C 5/342 (2006.01); G01N 33/00 (2006.01); G01N 35/00 (2006.01); G01N 35/04 (2006.01); G06T 7/00 (2017.01); G06T 7/90 (2017.01)
CPC G01N 21/251 (2013.01) [B07C 5/3422 (2013.01); G01N 33/389 (2024.05); G01N 35/0099 (2013.01); G01N 35/04 (2013.01); G06T 7/0002 (2013.01); G06T 7/90 (2017.01); B07C 2501/0063 (2013.01); G06T 2207/10024 (2013.01); G06T 2207/30181 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An automated gemstone color-grading machine comprising:
a rotating plate having mounts on a surface, the mounts each for supporting a gemstone;
wherein gemstones on the mounts include a sample gemstone and a series of master gemstones, wherein the series of master gemstones has master gemstones of varying known color grades;
wherein the sample gemstone has an unknown color grade that is between at least two of the known color grades of the master gemstones;
a step motor for rotating the rotating plate by one or more increments that are less than a full rotation;
an image sensor for capturing images of the gemstones on the mounts on the rotating plate;
a light source for illuminating the gemstones on the rotating plate;
a computer for instructing the step motor to rotate the rotating plate by an increment so that the sample gemstone is rotated to a position in the image sensor's field of view that was previously occupied by one of the master gemstones; the computer causing the image sensor to capture an image after each increment of rotation as the sample gemstone is successively rotated into all positions previously occupied by the master gemstones on the rotating plate;
wherein each master gemstone successively occupies positions of the sample gemstone and other master gemstones as the rotating plate is incremented;
the computer executing machine-readable instructions that cause the computer, for the sample gemstone and for each of the master gemstones, to select pixels for that gemstone from images captured by the image sensor after each increment of rotation, the computer averaging color indexes of these pixels for each gemstone over all incremented positions of the gemstone to generate a gemstone average color value for each gemstone, the computer selecting one of the master gemstones as a closest gemstone that has a smallest difference in the gemstone average color value for the sample gemstone and the master gemstone, the computer outputting an indication of the known color grade of the closest gemstone as a color grade of the sample gemstone,
whereby the color grade of the sample gemstone is determined by averaging color indexes from pixels of gemstones captured by the image sensor over different rotational increments.