How Cut Effects the Value of Ruby

It is nearly impossible to find a perfectly cut natural ruby in the marketplace.  There are two reasons.  One is that rubies are very expensive, precious and rare, so there is a hesitancy to cut off any more stone than absolutely necessary during the faceting process.  The other reason is that ruby forms in the earth's crust as octahedral crystals, that are usually wide and flat.  These two facts mean that cut rubies found in jewelry are usually cut too shallow.  You can sometimes see through them (called "fish eye"), where if it were cut at the proper angles and proportions, you would only see light and glitter reflected back to you.
A well cut ruby is exceedingly beautiful and hard to find.  You will know a well cut ruby when you see it because it will dazzle you with its sparkle. This is because when the facets are cut at the proper angles, they act as mirrors and bounce light all around the inside of the stone.  Unfortunately, cutting a ruby at the proper angles usually means grinding away a large part of the ruby (a very skilled cutter will cut away even 60%).  And since rubies are such valuable gemstones, most of the time gemcutters ere on the side of keeping the gemstone as large as possible, instead of being cut at the proper angles.  When you are looking for a ruby, you can use the following guidelines to help you assess the cut.  (Though, you should go in expecting a poor one.)
  1. Uneven facets: Rubies are usually given mixed or cushion cuts. Most of them are cut in south Asian countries by hand without the latest lapidary machines.  Look for some of the facets to be strangely shaped or for facets which "overlap", meeting at a line instead of one single point.  These are signs of a poor cut.
  2. "Fish eye": if the bottom ruby is not cut at the proper angles, you will be able to see through the ruby rather than seeing light reflected back to you.
  3. Dullness: Basically, you can tell how well a ruby is cut by how well it sparkles.  (This can also be affected by clarity, however)
  4. Shallow of Flat Stones: If you are able to see the ruby from the side and it is significantly wider than it is tall, you are looking at a typical bad cut.
Here are some illustrations of how the quality of cut affects the value of a ruby.

Poor Cut: This is an example of a "fish eye".  We can nearly see straight through this ruby instead of seeing the sparkle of light reflected back to us. Typical Cut:  This cut is similar to what exists in most jewelry: there is some sparkle but the facets are uneven. Perfect Cut:  This is a perfectly, beautifully cut ruby.  The lights play and reflect from every facet.  We cannot see through it: we only see sparkle. Every facet is even and symetrical.

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