Mint Tourmaline
Latest News
08/10/09 22:56 Filed in: Latest Cut
Gems
There seems to be some confusion with my new
grading system. Since the early spring of 2009 I
have moved to this new system based on Color,
Clarity and Brilliance. Not all three are a 1-10
scale. This is all explained on the information page, but
I think a lot of people never "read the fine
print", so I'm expaining the grading system
here again.
Color is the most important and complex to grade. Color is made up of three components, hue, saturation and tone. Color will be graded on a scale of 1 to 10 taking these three factors into consideration.
Clarity is graded on a scale of 1 to 10, with 10 being loop clean under a 10X loop.
10 = Loop Clean
8 = Eye Clean
6 = Slightly Included
4 = Moderately Included
2 = Heavily Included
Values between are used when the stone is either a bit cleaner or less clean. It's very rare to find any stone score a 10 for clarity. 7 and higher makes for a very nice stone.
Brilliance - will be a combination of Cut, Sparkle, light return, Proportion and Crystal.
Graded on a scale of 1 to 5, with 5 being the best.
Total Quality Rating - Is the combined score of these 3 with a possible best score of 10
1-5: Low end commercial
6-7: Better quality commercial
8-8.5: Fine quality
8.5-9.5: Very fine quality
9.5-10: What the trade calls "gem"
One new stone tonight, this is a mint green tourmaline for a new find in Nigeria. Nigeria is pretty famous for producing a variety of colors of tourmaline, but this is first I have seen this color. Hopefully this is just the start of these stones.
Color is the most important and complex to grade. Color is made up of three components, hue, saturation and tone. Color will be graded on a scale of 1 to 10 taking these three factors into consideration.
Clarity is graded on a scale of 1 to 10, with 10 being loop clean under a 10X loop.
10 = Loop Clean
8 = Eye Clean
6 = Slightly Included
4 = Moderately Included
2 = Heavily Included
Values between are used when the stone is either a bit cleaner or less clean. It's very rare to find any stone score a 10 for clarity. 7 and higher makes for a very nice stone.
Brilliance - will be a combination of Cut, Sparkle, light return, Proportion and Crystal.
Graded on a scale of 1 to 5, with 5 being the best.
Total Quality Rating - Is the combined score of these 3 with a possible best score of 10
1-5: Low end commercial
6-7: Better quality commercial
8-8.5: Fine quality
8.5-9.5: Very fine quality
9.5-10: What the trade calls "gem"
One new stone tonight, this is a mint green tourmaline for a new find in Nigeria. Nigeria is pretty famous for producing a variety of colors of tourmaline, but this is first I have seen this color. Hopefully this is just the start of these stones.
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