Girdle charts

[pyramid]

http://www.gis.net/~adamas/cut.html#girdle

Can someone explain these charts in laymans terms please?

Is base diameter = diamond diameter?

What does the two charts show us is it stepping of the girdle in different weight diamonds

and then thickness of the girdle

Does the actual line widths mean anything in relation to the diamond?

 

[Garry H (Cut Nut)]

AGS is 100% transperent - they publish a girdle thickness chart based on the thickness as a % of diameter. A 10mm diamond with a 0.15mm girdle is 1.5% thick, but say that a 1.5% girdle is a nice medium size, but 1.5% is very thin on a .30ct diamond and very thick on a 20ct diamond.

Marty has tried to crack the GIA code for their method. they use in theory a visual expert assessment - but Marty has shown they probably use a non contct measurement device (like Sarin) to simply measure the mm thickness - and unlike AGS, they would give a girdle thickness based on the mm thickness - irrespective of the diameter.

 

[pyramid]

Thanks Garry H.