1) They always have been rare, actually: "Rubies are the most valuable members of the corundum family. Large, gem quality rubies can be more valuable than comparably sized diamonds and are certainly rarer. Small gem quality rubies are rarer than comparable blue or other color sapphires, making even the littlest fine rubies relatively high in value. Many gems increase exponentially in value with increase in carat size, and this is particularly true of fine ruby gems. Of course there is a tremendous amount of lower quality ruby available in the market for reasonable to lower prices. Stones of Burmese origin generally command the highest prices. Strong color saturation, eyeclean or better clarity, and strong fluorescence elevate prices sharply." Source and further information: http://www.bwsmigel.info/GEOL.115.ESSAYS/Gemology.ruby.html 2) The dark side of rubies: "Of the world's rubies, 90% currently derive from Myanmar (Burma) whose red stones are prized for their purity and hue. Thailand buys the majority of Myanmar's gems. Myanmar's "Valley of Rubies", the mountainous Mogok area, 200 km (125 miles) north of Mandalay, is noted for its rare pigeon's blood rubies and blue sapphires. But working conditions in the mines are horrendous. Debbie Stothard of the Alternative ASEAN Network on Burma stated that mining operators used drugs on employees to improve productivity, with needles shared, raising the risk of HIV infection: "These rubies are red with the blood of young people." Brian Leber (41-year-old jeweler who founded The Jewellers' Burma Relief Project) stated that: "For the time being, Burmese gems should not be something to be proud of. They should be an object of revulsion. It's the only country where one obtains really top quality rubies, but I stopped dealing in them. I don't want to be part of a nation's misery. If someone asks for a ruby now I show them a nice pink sapphire." In 2007, following the crackdown on pro-democracy protests in Myanmar, human rights organizations, gem dealers, and US First Lady Laura Bush called for a boycott of a Myanmar gem auction held twice yearly, arguing that the sale of the stones profits the dictatorial regime in that country." Source and further information: http://en.wikipedia.org/wiki/Ruby

Rubies have been the rarest of all gemstones since the time it was discovered. And an excessive use of ruby can make them completely invisible.