Tolkowsky Mearsurements vs. HCA Rating

[Anniversary Girl]

If the ideal Tolkowsky table range is 53 - 57%, how can a diamond with a 58% table still get a 1.0 HCA rating? Is that an error?

 

[belle]

there are ''ideal'' diamonds, ones that would get top grades from both gia and ags, that have tables above 57%. hca results reflect the angle combinations needed for a 58% table to perform well.

 

[Anniversary Girl]

Thanks, Belle! I was hoping that was the case. It is so scary to purchase a diamond when you know next to nothing. I should change my screen name to "Clueless in Seattle" instead of Anniversary Girl. LOL.

Thanks again.

 

[belle]

you''re welcome ag!
it doesn''t have to be scary. just take your time and ask lots of questions. there is much information here.

 

[pricescope]

Anniversary Girl, original Tolkowsky proportions have 53% Table and knife edge girdle.

In the real life, diamond should have some girdle to avoid chipping and table can be larger without sacrificing the light performance and increasing spread.

You can read more about girdle, table, and Tolkowsky proportions at Jasper'' site: http://www.folds.net/diamond