1. Gemstones may have been treated by heating (generally), or diffusion (sapphires) to enhance the color of the stone.
2. Blue, yellow and red coloured diamonds have been irradiated to achieve their color. Color treatments used on diamonds may be sensitive to high temperatures and heat.
3. Created gemstones are grown in strictly controlled laboratory conditions to recreate the brilliance of rare natural gemstones.
4. Enhanced blue turquoise stones are treated with a dye to enhance the natural blue color.
5. Black diamonds are enhanced by high temperature to permanently create the intense black color.