Ruby 3.5mm Round. Ruby is one of the most rare minerals on Earth. It is also one of the hardest of materials, tough and durable. When also a thing of beauty, no wonder it is costly. And no wonder there is so much fakery of it out on the market, be it totally man-made in the form of synthetics, or lead glass filled material (which can greatly improve very poor gemstones but leave bubbles visible under a good lens), or simply the attempt to pass simulants off as the real thing, simulants such as reddish Spinel or deepish pink Sapphire, or even glass.
All natural Ruby has inclusions. The pair of Rubies set in the above White Gold earstuds are natural Rubies of good red colour.