刚刚又看到一篇标准，真是头大阿，每篇都不一样。我总结一下。
■Color: I Color or better. H Color or I Color with a Princess Cut will give you the best value. Going higher in diamond color (to D, E, F, or G Diamond Color) will give you an incremental benefit, but I’m not convinced it’s worth the incremental price. I don’t recommend J color with Princess Cuts because they retain color slightly more than Round Brilliants.
建议I色以上，h色或者I色的公主方钻最合算。高色的钻石d，e，f或g会增加钻石的价值，但是不能保证这个增值价，不建议j色。
■Clarity: Stick to VS2 clarity or SI1 clarity for the best value. SI2 and I1 clarity Princess Cut diamonds are in very short supply due to the high quality of diamond rough that Princess Cut Diamonds are cut from. If you can find one, and verify that it’s clean to the eye (with, for example, James Allen’s Virtual Loupe), then that’s even better. VS1, VVS2, VVS1, and Internally Flawless (IF, or FL) are great, but why spend more money if they all look the same (clean)?
vs2， si1就够了，不要多花钱寻求净度高的，应为看起来也差不多。

■Cut Parameters for Princess Cut Diamonds: ■Depth: 65% to 75% (under 70% is very hard to find)
建议depth：65%-75%， 70%很难找到
■Table: Below 75% (There are two schools of thought on this, the Small Table school and the Normal Table School. Try and look at both – below 68% table and above 70% table and see what you prefer. Just one note – small tables are much harder to find)
table要低于75%，2个学校有不同标准，看你喜欢那个，低于68%和高于70%，小的table比较难找。
■Polish/Symmetry: Good, Very Good, or Excellent
抛光，对称：好，很好，完美（这个等于没说阿)
■Length/Width Ratio: 1.00 to 1.05 for Square Princess Cut
长对宽比：1-1.05，这个和我上面说的一样了。