Proportion Scanners

Optical scanners measure a diamonds dimensions and proportions quickly and accurately. A diamond is placed table down on a rotating stage and a video camera captures images from a collimated light source behind the diamond. The more images captured the more accurate the scan. Some scanners are designed for speed and some for accuracy. The three main companies that manufacture scanners are Sarin, Ogi and Helium. Serge who posts here on technical diamond cut related topics is the CEO of OctoNus, who together with Lexus make Helium which GIA grading labs have begun buying in large quantities.

Labs all use scan data to establish their symmetry and cut grades. GIA use the proportion data and a look up table the same way that HCA and the HCA app function. The American Gem Society (AGS) use a 3D model of the diamond to estimate the diamonds potential beauty using its proprietary data base (AGS PGS) that estimates various light performance and other factors.

GIA also uses the data it collects to “finger print” diamonds in its Horizon program to screen for resubmitted diamonds; e.g. dealers hoping for a better grade.

There can be variations in HCA results based on the accuracy of the scan data.