Help me understand the HCA!

[Kath]

Hi All - I''ve learned so much from this forum already, enough to realize that the HCA calculator is very important to determine a diamond''s brilliance, fire, etc. I''m planning on buying a .4 carat, ideal cut, F, VS2, round brilliant diamond from a local wholesaler, but I''m a little unsure how much weight I should put on the HCA score when I make my selection. I''ll only have a limited number of diamonds from which to choose, so I''m wondering what to do if none of the ones I have to pick from get a score of under 2? Is a Very Good score also going to give me a brilliant diamond, just not AS brilliant as an Excellent score, or if I get a Very Good score should just throw out that diamond and try to get more selections brought in?

Please help me understand the HCA''s importance in this whole process!

 

[Lorelei]

My take on this and I am sure Garry and Belle etc can give you a better explanation is that the HCA is a useful tool for eliminating diamonds which may not perform quite as well as others, but it is no substitute for your own eyes. Equally a great score won''t guarantee that a diamond is beautiful, just indicates that it COULD be. An Idealscope is also available which is very useful for helping determine a well cut diamond. JMO use the HCA as a tool to help you, but if a diamond doesn''t have the highest score and you love it, that is all that matters. The HCA is great for online purchasing where you can''t actually see the diamonds to weed out the lesser performers. Try not to worry too much about the numbers, the eyes have it! Also you could drop the clarity if you wanted to an SI1 for example and still have a great chance of getting an eyeclean diamond. Also you could drop the colour a bit too if you wanted,say to a G or H will still look very white, just to enlarge your options. Does the vendor have Sarin reports on each diamond? This would help too.

 

[belle]

lorelei is spot on.
you have the opportunity to correlate what your eyes are seeing with representative scores on hca. i do hope you will get a chance to see stones in the under 2(ex) and 3(vg) range for comparison. is your wholesaler going to be able to provide the information needed in using the cut advisor? keep in mind that angles are more accurate than percentages when using the hca. most importantly, as lorelei suggested, let your eyes decide. if you pick a stone that happens to not score well on the hca, it doesn''t mean the stone is bad, or less brilliant because hca cannot predict beauty or your perception of it. best of luck!