Counterintuitively, the dye produced from brown avocado stones is pink, with shades ranging from the softest shell blushes to deeper rosy hues. The colour comes from the shells of the avocado stones, which are rich in tannin. Avocado is the principal ingredient used by Venezuelan-born María Elena Pombo for her Fragmentario brand, and she also produces dyes from onion skins and annatto seeds. Working under laboratory conditions, she experiments with water of different pH values to discover how this affects the colours produced. Natural dyes can be very unpredictable, and Pombo has worked with commercial producers to make scalable dye recipes.