I like Joseph P. Stachura Co. for cabochons.
They are nice folks to deal with, and put out a cute little catalog.
I get moonstones, garnets, amethysts, topaz, and a variety of opaque
stones. They might not be perfectly calibrated, but they are pretty,
and the price is great. If you are making your own settings, you
will like them. I buy bags of a dozen, and can thus match them up if
I need to for earrings. They have faceted stones, and have beads,
also. (just a happy customer)