The IGI started out as the blue color workhorse of the diamond business. They were, and still are, the most popular gem lab for the major jewelry chains in the US and Canada (Kay, Zales, etc.) They are like a factory. They work fast, and they work cheap.
Lately, though, they have been trying to position themselves as a legitimate contender against the other labs and not just a certificate factory for the major chains. While they haven’t succeeded so much in America, they have actually gained quite impressive market share in Europe and the Middle East. I used to travel to sell diamonds in Dubai, and the two major certificates sold in that market are HRD and IGI.
The bottom line with IGI in comparison to GIA is that they are consistently looser in color, and partially looser in clarity. What I mean by this is that specifically in the “SI3″ range, they generally upgrade to an SI2. Diamonds used for “SI2″ programs at the major chains would almost never pass a GIA “SI2.” I know this particularly well, as throughout my professional career, I must have personally selected thousands of diamonds to be sold as IGI SI2s at the major jewelry store chains in the US and UK. These programs (usually the middle-ground price point offering great value as it’s the cheapest of the eye-clean grades) all have a minimum of SI2 clarity. For these programs, we would always strive to find diamonds that were in that “SI3″ sweet spot — diamonds that would not receive an “SI2″ from GIA, but were too nice to sell as an “I1.”
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