Working with Cabochons and Rose Cuts

If you are used to working with only faceted stones, you’ll find that cabs and rose cuts are an entirely different animal.  Very little of what you know transfers over to the non-faceted gem world.  Cab pricing and weighs are different, they are judged on a different scale, and most commercial settings don’t work.
First, be aware that cabs and rose cuts are not usually clean gems.  The facet grade rough is – well – faceted, and cabs are the next grade down before rose cuts and then beads.  Cabochon material is therefore rarely as clean as faceted stones.   The quality often ranges from very good (near facet grade) to very poor (totally dead and opaque).  Obviously, I don’t recommend the latter.  Cabs don’t have brilliance either, rather, when set right, they glow, despite inclusions.  Cabs usually rank better in terms of glow than rose cuts because the facets of rose cuts don’t let the gem be as bright.  And of course the term “window” doesn’t apply because to not have window, you need back facets.  Technically, therefore, all cabs and rose cuts have window. 
Spinel Rose Cuts
When you buy cabochons, you can expect a lower per carat price than for faceted stones, but you also need to expect them to weigh more.  On average, cabochons weigh twice as much as faceted stones in the same size.  The exception are rose cuts, because they are flatter and the top facets remove extra weight.  The facets hide flaws, however, so your expectations of a rose cut should be lower than that of a cabochon.  Rose cuts usually weigh about the same as faceted stones.  Often, though, a high quality cab and a low quality faceted stones can come out the same in terms of price.
Finding the right setting for cabochons can be challenging.  Even calibrated stones often do not fit the settings that are fabricated for their size.  Many are too high so that the bezel wall doesn’t fold over right; or they are too low so that the stone vanishes under the bezel wall.  Yet others are slightly too big or too small – the latter applies to rose cuts in particular.  The smaller the cabochon, the more problematic it is if it doesn’t fit right.  So when you choose cabs, watch for high dome and low dome, as the terminology goes.  If you have a bezel already, bring it with you when you buy the stone and see how the stone looks in it. 
Round Commercial Bezels
Add to that, that many cabochons are not calibrated in the first place.  So you have to expect to be making the bezel by hand.  This is even more the case for rose cuts, which are often cut in irregular shapes, just following the natural lines of the material.  The expectation is that for either, you will make your own setting, or have it made. 
When I make bezels for cabs and rose cuts, I usually do a closed back.  I find that many gems look washed out when there is no metal behind them.  The light simply passes through them and that dulls the color.  The exception, for me, is when I channel set cabs for earrings, because then I like the light to pass through.  A ring or a necklace has your skin behind it at all times, and that doesn’t help the stone reflect out.  In earrings, that is not a concern.
Square and Oval Cabochons, Cabochon Bullet