How does grading work?

[sierrachang]

I am a newbie, but I thought that if you had a diamond that was heavily included it should be dull and dead. I just saw the junkiest stone (I2) with the most inclusions sparkle like I never saw. It''s clear and not cloudy, but it has lots of black carbon. I thought the carbon blocks the light and wouldn''t be bright.

It has a lot of fire. How is this possible?

Thanks! I''ve got lots to learn.

 

[Todd07]

Beauty is all about cut. That's why the Cut Adviser does not ask about clarity or color.


Read this in the education forum https://www.pricescope.com/forum/ed...diamond-eye-catching-or-beautiful-t15002.html

 

[oldminer]

Ricardo07 has it somewhat right, but color and clarity DO play a role in overal light performance. If you took a black, opaque diamond, and entered the parameters into the HCA, you would get a light performance figure based on a nearly colorless and very transparent diamond. It would be VERY INCORRECT.. The same thing would happen with a cloudy diamond or a strong fluorescent one. The HCA and other predictive tools cover the ground on the vast majority of gem grade, nearly colorless and transparent diamonds, but like many tools, it does not work for a smaller pecentage of diamonds for one or more reasons.




If you are looking at the normal range of diamonds, the HCA can help you a lot. If you are on the fringes, such as with an I2 diamond, you can readily be fooled unless you have a comparision diamond nearby. The strong lighting in some stores also can throw off your ability to see into the diamond because of the high amount of surface reflection.




I would go out on a limb and say NO ideal cut I2 has light performance equal to an identical ideal cut of SI1 clarity. This is an apples to apples comparison with only clarity being the variable.




We do see MANY I2 diamond being sold by mass marketers. People love these rocks just like others who have much finer stones. Sentimentality does not care about clarity. It is the thought that counts.

 

[Todd07]

I'm a rough rock and humbly take the correction.

I was trying to make the point that cut explained why you saw an I2 sparkler, but went overboard in insinuating color and clarity didn't play a role in beauty. A D IF can be a dud in sparkle while your I2 looks great, from a distance.

 

[Upgradable]

OMG, Alexah!!!! That stone looks like it's decorated for a Chinese Restaurant!

 

[Garry H (Cut Nut)]

It is written somewhere in some course notes (GIA?) that I2 is generally considered to be the clarity level where diamond brilliance begins to be reduced by the prescence of inclusions.

Sometimes you will find a cloudy SI2 that is dulled.

Sometimes a Imperfect diamond has an inclusion that makes the diamond sparkle more because it catches the light and reflects it back