Of all the most essential colors of the palette, this one makes our short list. The synthetic version is God’s gift to painters as it replaces and in many respects, succeeds, the extremely expensive Lapis Lazuli. There is no other pigment quite like it—a transparent royal blue that leans violet. Where cobalt blue has a feeling of solidity, ultramarine sparkles like tanzanite. We’re grateful for the discovery of synthetic ultramarine as it's hard to imagine what it would be like to be without a deep, rich blue at the ready. Natural Ultramarine from Lapis Lazuli shares the same pigment code, however it tends to look quite different as an oil paint. We’ve given Natural Lapis a separate entry in the pigment notebook.

Synthetic Ultramarine is a phenomenal deep blue. It's transparent, dark in masstone, chromatic in tints, and varies a bit from a middle blue to an indigo-violet. We compared a handful of varieties in oils here.

There are many shades within this pigment code but there tend to be two main forms. Of the two, one is slightly more reddish than the other— the "redder" shade is more violet, and is often labeled Ultramarine Blue Deep. Alternatively, in the English world, paintmakers may name the redder version “French”. It has excellent lightfastness, however it does have a few tricks up its sleeve in oils. There is also something called ultramarine sickness which describes some changes that can occur to the paint. However there don't seem to be any viable alternatives, and for most intents and purposes ultramarine behaves itself. For some wildcards regarding ultramarine, see Golden's recent lightfastness testing.