Lorridan gemstones are the result of years of subjugation suffered by the Lorridans. Banned from speaking, the Lorridans developed a form of communication centered around subtle gestures and ticks. Lorridans attuned to the Force imprinted these gemstones with Force energy in order to assist them in reading others.
Once the Jedi freed the Lorridans from their oppression, they discovered these Force-sensitive Lorridans and their unique gems. In fact, there were occasions in which Jedi Knights used these gemstones as the focusing crystal in their lightsabers.