Question about HCA tool!

posted 3 years ago in Rings
Post # 3
Member
164 posts
Blushing bee

@MissSweetiepie:  Not all GIA Excellent cut grade diamonds are created equal. In fact compared with the AGS ideal cut grade, GIA’s grade is quite broad. The HCA is meant to be a rejection tool to weed out the lower performing ones. It also has its own ‘preferred specs’, so a high HCA score doesn’t make it a bad stone for a fact, rather it predicts that there are better ones out there.

There are many combos of angles that make a great performing stone, each with their own characteristics (more fire or brilliance for example).

That being said, your stone’s pavilion angle is steep when combined with the crown angle. Generally speaking, a good combination for a 35 crown would be 40.6-40.8 pavilion. A 41 pavilion would complement a 34.0-34.5 crown well. A 59 table is considered to be on the larger side

It’s difficult to make an assertive comment since GIA rounds the numbers (for example, a 41.15 pavilion becomes a 41.2, which is actually significant). I doubt it would have made the AGS ideal cut grade, but then again I’m not an AGS grader and I don’t have the stone.

To be clear, I don’t mean to put down your diamond in any way! The HCA is primarily used for people who are trying to narrow down diamond choices. A score below a 2 actually means that it’s worth investigating the stone further (with an idealscope/ASET). It’s by no means a perfect tool. You have your diamond already, so unless you’re seriously considering returning it for another, just enjoy it!

I recommend making a thread on Pricescope, I have nowhere near the amount of experience experts there do. Garry Holloway posts on occassion too, so you can ask the HCA creator himself.

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