If, like us, your email inbox and Instagram feed is taken up by gemstone-related pictures, videos and articles, then you’re well aware that emerald is the birthstone for May. Scrolling through Instagram there’s no shortage of beauties hailing from Muzo or Belmont or Sandawana, so we thought that given it’s almost the end of the month we would join in.

A few months ago, we were lucky enough to come across a large cat’s eye emerald. Incredibly rare, they have been recorded in Colombia and Brazil, with possible sources in Africa. It was big, rich and displayed beautiful chatoyancy.

There is not a lot of literature on the crystallization of cat’s eye emeralds. It is generally agreed that they are actually a single tranche of a trapiche emerald, as its hexagon shape is not due to asterism but is made up of six sections each with the potential to display chatoyancy. Chatoyancy itself is due to many, many fine parallel tubes creating inclusions so dense that light reflected off the surface of the cabochon creates a single line that moves with the stone from one side to the other (the cat’s eye). The optical phenomenon is common in chrysoberyl, tourmaline, quartz, moonstone… but is far less common in emeralds.

Unfortunately we were a bit overexcited so instead of measuring the stone we took photos. This kind of material gets snapped up instantly, so it wasn’t long before we had to say goodbye. If any of you are on the hunt for your own cat’s eye emerald, get yourself to a gem fair (the next major one is JCK Las Vegas starting next week).

Disclaimer: due to bad lighting and overexcitement the pictures are not fantastic. But if you check out our Instagram, there is a video of the cat’s eye in action!