These are faceted light grey moissanites with a spot of dark green-black right in the center, giving them the appearance of an eye! They are available in calibrated sizes and as individual stones.
This is moissanite, also known as silicon carbide. It is an excellent gem, with incredible hardness (around 9.25-9.5) and greater brilliance and fire than a diamond. It is perfect for use in all kinds of jewelry, even engagement rings.
Though it is well known in the gem world it is also highly valued in the world of science and industry. It is a semiconductor just like pure silicon but far more durable and heat-resistant, so it is used to make computer chips that need to endure high stress environments like in a car engine. Fortunately for us these uses require very exacting standards and sometimes crystals are rejected.
These were cut from a very unusual failed crystal which was nearly colorless except for a very dark top layer of green-black. When cut as rounds with the dark spot right on the culet they have the striking appearance of an eye looking back at you! I don't know if we'll ever find another crystal that failed in just the right way to have more cut.
