Onyx rings

Onyx

— one of the varieties of quartz, in many respects similar to agate (see the relevant paragraph) — to the extent that the same mineral can be called both agate and onyx. A distinctive feature of natural onyx is its unusual structure: impurities form layers of different colours in the mineral, which are clearly visible in the section. However, for the layered structure to be noticeable, the stone must be quite large — and in the case of rings, this is inconvenient. Therefore, jewelers usually choose monochromatic fragments of onyx for rings — most often green. Such a stone at first glance may be indistinguishable from an emerald.