People often wonder "what makes a good gemstone" so I've decided to write a series of short blog posts about various gemcutting or gemology topics - in no particular order. Here's the first installment, showing an easy way to visually determine a cutter's commitment to detail by examining a gemstone's crown facets.
Most "western" cutters learn what's called meetpoint cutting - that is, cutting each facet until it precisely "meets" or joins adjoining facets. When done properly it is a work of beauty; when not, not so much. Many cutters will take shortcuts, particularly when it comes to the crown facets that meet the table (the"star" facets on a round brilliant cut). It's fast and easy to cut the table a bit short and avoid all those pesky meetpoint details, or cut to just one or two meetpoints correctly, ignore the rest, and assume that the customer won't notice the difference (because many customers don't know what to look for). Even the often derided "native" cutters will cut a good looking crown because that's what the customer will see after the stone is mounted. It doesn't take much additional time to finish the meetpoints correctly, but for too many cutters "time is money" and consequently prioritize quantity over quality.
Here are some examples (both good and bad):
So you see that's really quite easy to judge some aspects of cut quality from a quick examination of the gemstone (and often a photo will suffice). Of course, there will always be some exceptions where cutting constraints that might prevent perfect meetpoints - for example, repolishing a badly cut stone that had poor symmetry or to avoid inclusions just under the table. However, for the majority of stones (and especially those cut from rough) there should be no excuse for poor table meetpoints.