Galahad is described as a mystic vibrant blue green, and it's almost a perfect match to a dark turquoise bracelet that I own. Most turquoise that you see is lighter, like this ring. This is two coats with Seche Vite base and topcoat. A steadier hand may have been able to get away with one coat, but my polish skills are still a bit lacking.
a-england polishes are available direct for about $14.45 (prices are listed in British pound sterling) or through Llarowe for $12. a-england shipped for free in the past from their site, not sure if that's still the case.