Tanzanite is most prized for its mesmerising blue-violet colour, which ranges from deep indigo to light lavender. Its colour is influenced by pleochroism, which means it displays different colours when viewed from different angles. This unique feature adds to its allure and makes each tanzanite gemstone a one-of-a-kind piece. The gemstone's clarity is also highly valued, with transparent and eye-clean specimens being the most desirable.