There is no other pigment quite like synthetic ultramarine blue—a transparent royal blue that leans violet. Where cobalt blue has a feeling of solidity, ultramarine glistens like tanzanite.

So we're suckers for natural pigments too, but when it comes to this pigment, we’re especially grateful for the discovery of synthetic ultramarine. We can hardly keep from saying prayers of thanksgiving for this Godsend to the palette. Just imagine having to trade your car for a tubes of the highest quality natural lapis lazuli, or going without groceries for week (we hate to say it but most of the natural ultramarine on the market can't hold a candle to the synthetic version... and even the mediocre natural versions are not exactly affordable). As a painter, it's hard to imagine what we'd do without a deep, rich blue at the ready. Of all the most essential colors of the palette, this one makes our short list. The natural one is loads of fun too, so be sure to check out the entry we've dedicated to it over at Lapis Lazuli.

Ultramarine Blue is the synthetic version of a natural ground stone which can be made into pigment. While the natural version has its charms, the invention of synthetic ultramarine was an incomparable boon to painters. In depth and vibrancy it rivals the most expensive grades of Lapis Lazuli. Since Lapis Lazuli shares the same pigment code but looks so different when made into 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. For details on the wildcards regarding ultramarine, see Golden's recent lightfastness testing. There is also something called ultramarine sickness which describes some changes that can occur to the paint, however that is fairly rare. As there don't seem to be any viable alternatives in the color space, and for most intents and purposes ultramarine behaves itself.