The price of yellow sapphire is influenced by several factors, including origin, clarity, color, carat weight, cut, and treatment. Sri Lanka is considered the best and most expensive source for yellow sapphire due to its exceptional clarity and color consistency. Thailand, Burma, and Africa are other sources, but the color concentration and presence of inclusions may vary. Clarity, color, and carat weight also play a role in determining the price, with cleaner and bigger stones usually commanding higher prices. Additionally, the presence of treatments and enhancements can affect the value of yellow sapphire.