What are "ideal" dimensions for large Marquise

[BKG6053]

I hope to purchase a large (1.75 carat) Marquise loose diamond on-line in the coming weeks. However, I am trying to determine what/how to calculate length x width, depth, table, etc. for this type stone. In other words, I am very concerned I will miss my target on ''cut'' and will select a stone less than "ideal". Surely, there must be a formula whereby length x widht can be measured to provide maximum appearance, brilliance, etc. Any help would genuinely be appreciated! Here or [email protected].

 

[oldminer]

Please visit my website for the cut parameters of the nicest marquise shaped diamonds. There is an AGA Cut Class chart which covers marquise, pear and oval. The 1A and 1B ranges will result in great looking shapes along with the potential for best light performance. Parameters do not necessarily equate to performance, but a poor shaped diamond that performs well would not only be rare, but probably not beautiful either.

There is a Shape Selector tool on the site, as well. This will assist you in establishing what your own Length to Width preference ratio range might be. Some folks want a short, fatter stone and others might want a more canoe, needle shaped diamond. Most prefer the moderate, balanced approach. My cut grading charts don't force you into selecting a diamond whose outline is not to your personal tastes, but the tool there will give you some help. You can fiull in the measures fields and see the outline change when you click on clculate or you can just use the sliders to seem what L:W ratios look like in a more general way.

There are no Ideal Standards of light performance with marquise shaped diamonds as of today. ImaGem, a firm I consult with, is nearly ready to publish the marquise performance number sets, so we are nearly ready to set that standard ahead of the pack. A few more weeks, I suppose, and those numbers willl be put forward.

For those of you who have been keeping watch on ImaGem, the numbers for the various light behavior classifications of princess cuts have now been added to the website and are also in use in my lab and in the ImaGem lab in Surat, India.

 

[strmrdr]

Work with a vendor that uses the ideal-scope or other similar scope and evaluates the diamond in person and have them call a couple in is the best way to find a nice one.
Id start with:
www.goodoldgold.com

or

www.whiteflash.com

or

www.jamesallen.com

 

[oldminer]

The suggestion of those vendors is not a bad one. However, each vendor will make their own judgments about what they consider their best looking or best performing diamonds. When I see a consumer ask for "Ideal" I assume they don''t realize that no international standard of performance yest exists. Knowledgeable dealers can be a great assisitance in helping aconsumer to select a beautiful diamond, but we should not infer that any of these are what the consumer requested, "Ideal".

"Ideal" to me is the BEST and we do need standards to represent diamonds in this way with that special term. I hope this further explanation makes people better informed.

 

[strmrdr]

Well the consumer can get the IS or LS image and post it here and you can tell em if its "ideal"
Hows that?

 

[Hest88]

Definitely go to Dave Atlas'' site as a first step. It will help you weed out the worst offenders and give you some parameters to aim for.