Red

We generally do not purchase ruby or sapphires have been diffusion or beryllium treated, always exceptions though when we see a standout stone. The finest rubies look like someone painted a swatch of fluorescent red directly across them. It is an almost glowing red, diffused well through the stone, and is rooted from the unique property of fine Rubies, a rich red fluorescence. While Burma (or sometimes called the Mogok Ruby) is the traditional source for the finest rubies, good stones are a rare find anywhere, the best stones contain tiny amounts of rutile silk which give these rubies their awesome crimson glow. Some neat facts and lore concerning rubies:

At Sotheby’s New York’s October 18, 1988 sale, Alan Caplan’s 15.97 ct Burmese ruby sold for $3,630,000, or a startling $227,301/ct (most of ours are less!)
Few named rubies:
167 carat Edwardes ruby (British Museum)
100 carat DeLong star ruby (Am Mus Nat Hist)
138.7 ct Rosser-Reeves star ruby
Many believed that rubies possessed an inner flame which burned eternally.
The Burmese believed rubies ripened like fruit, and that the redder a ruby, the more ripened it was. If a ruby was flawed, it was considered over-ripe.
Although The Black Prince Ruby sits in the Imperial State Crown in London, it is actually a 170 carat spinel