Second driver of quality is the clarity. This is all about inclusions in the gemstone. All natural gemstones have inclusions. Collectors search for gems with the least amount of inclusions, these are the most valued. However, sometimes a unique imperfection becomes the value factor e.g. horsetail inclusions.
Diamond clarity is well standardized. This standard can not applied for colored gemstones – they would all be of poor clarity. To complicate matters, the is no international standard for clarity of colored gemstones. As a result, organizations grade clarity differently.
Here we apply standard from Gemval.com. Note that colored gemstone clarity is judged in terms of how clean it appears on naked eye, not on loop.
Suggested Clarity Grades for Colored Gemstones (Gemval.com standard):
VVS – Very Very Slightly included = Eye clean 1 (no visible inclusions)
VS – Very Slightly included = Eye clean 2 (few tiny inclusions)
SI1 – Slightly included 1 (few small inclusions)
SI2 – Slightly included 1 (a few medium inclusions)
I1 – Included 1 (multiple large inclusions)
Clarity definitions by Myanmar certifying body (Stalwart Gem Laboratory) – under the microscope:
Lightly Included (About VVS, VS)
Slightly Included (About SI1,2)
Heavily Included (About I)