The number associated with the official Tiffany Blue color is 1837.
Tiffany Blue is the distinctive light, robin-egg blue associated with Tiffany & Co. Pantone produces it as a private custom color for the jeweler, designated PMS 1837. The number is not a random shade identifier: it refers to 1837, the year Charles Lewis Tiffany and John B. Young founded the company in New York.
The color’s association with Tiffany began early in the company’s history. It appeared on the cover of the Blue Book, Tiffany’s annual jewelry catalog, first published in 1845. Tiffany later made the shade central to its packaging, advertising, storefronts and other brand materials. The company registered Tiffany Blue as a color trademark in 1998.
A common mix-up is treating 1837 as a universal public Pantone swatch or as a hexadecimal color code. It is a proprietary brand color; the familiar digital approximation is often listed as #81D8D0, but that is not the same thing as the private Pantone standard.