I just reviewed the sapphire choices for this holiday season and they are all over the place. I mean every color on the spectrum is represented this year. That is how you know you have natural sapphire though, if all your blue colors are the same than you have a man made lot of sapphire. I have been to trade shows and there are vendors from other countries, you can guess where, selling multi stone necklaces that have all the exact same color blue sapphire for 10’s of thousands of dollars. When I ask the vendors if they are natural sapphire they look me straight in the eye and say yes, they are natural heated sapphire!???? Moral of the story, never buy sapphire that looks to perfect or matches all the other sapphire perfectly without professional help.
Here are some Sapphire facts from Wikipedia, they have some great pictures of the many colors of sapphire as well.(see link below) https://en.wikipedia.org/wiki/Sapphir
Sapphire is a gemstone variety of the mineral corundum, an aluminum oxide (α-Al2O3). Whilst typically associated with the color blue, natural “fancy” sapphires also occur in yellow, purple, orange, and green colors; “color change sapphires” show two or more colors. The only color which sapphire cannot be is red – as red colored corundum is called ruby, another corundum variety.
Trace amounts of elements such as iron, titanium, chromium, copper, or magnesium present during formation are responsible for the color of a sapphire. Chromium impurities in corundum yield a pink hue.
Rubies are corundum which contain chromium impurities that absorb yellow-green light and result in deeper ruby red color with increasing content. Purple sapphires contain trace amounts of vanadium and come in a variety of shades. Corundum that contains ~0.01% of titanium is colorless. If trace amounts of iron are present, a very pale yellow to green color may be seen. However, if both titanium and iron impurities are present together, and in the correct valence states, the result is a deep-blue color.