MAC How Royal is a moderately cool-toned, medium-dark blue with a pearl finish. It is a discontinued eyeshadow that retails for $17.00 and contains 0.05 oz.
MAC How Royal Eyeshadow ($16.00 for 0.05 oz.) is described as a "pearly cerulean blue [with a Veluxe Pearl finish]." It's a bright, medium blue with subtle, cool undertones and a pearly sheen. It had good pigmentation paired with a softer consistency that wasn't too firm or too dense, but I did notice it had a tendency to fade when applied to bare skin. Over primer, it looked better and applied more evenly. On me, it wore well for eight hours (no primer). KVD Beauty Paranoid (DC, $21.00) is less shimmery, darker (90% similar). Make Up For Ever S214 Ultramarine Blue (DC, $21.00) is less shimmery, darker (90% similar). Fenty Beauty Glacier Gang (LE, )(90% similar). NARS Showgirl (P, $19.00) is more shimmery (90% similar). Shiseido Esmaralda (BL 620) (P, $25.00) is more muted (90% similar). Sephora Rio (LE, ) is lighter (90% similar). Sugarpill Afterparty (P, $13.00) is darker (85% similar). Disney by Sephora Blue Lagoon (LE, ) is more muted, warmer (85% similar). Urban Decay Clash (DC, $20.00) is lighter (85% similar). MAC Blue Calm (DC, $17.00) is darker (85% similar). See comparison swatches / view dupes side-by-side.
FURTHER READING: Formula Overview, which is a detailed review of the range as a whole.
M·A·C Eyeshadow is a highly pigmented powder formula that applies evenly and blends well. Suitable for use either wet or dry, it's available in a wide variety of textures and finishes.