Not all gemstones seen on the market are from Mother Nature. There are a few, that are called gemstones despite the fact they are not, they are creations of man. A few of these are quite beautiful and very pretty when combined and used in jewelry.
.
It so happens that this jewelry set is constructed out of one of these man-made stones - Goldstone. Flat Goldstone discs form the center and highlight the sides of this necklace. Round Blue Goldstone combined with black Agate (Onyx) are used to complete the necklace along with a copper toggle clap. French hook dangle earrings with matching Blue Goldstone and Onyx finish the set..
Goldstone is a type of glittering glass made in a low-oxygen reducing atmosphere. The finished product can take a smooth polish and can be carved into beads, pendants, figurines or other artifacts suitable for a semiprecious stone, and in fact Goldstone is often mistaken for or misrepresented as a natural material. The most common form of Goldstone is reddish-brown, containing tiny crystals of metallic copper that require special conditions to form properly. The initial batch is melted together from silica, copper oxide, and other metal oxides to chemically reduce the copper ions to elemental copper. The vat is then sealed off from the air and maintained within a narrow temperature range, keeping the glass hot enough to remain liquid while allowing metallic crystals to precipitate from solution without melting or oxidizing. After a suitable crystallization period, the entire batch is cooled to a single solid mass. The best material is near the center or "heart" of the mass, ideally with large, bright metal crystals suspended in a semitransparent glass matrix. Goldstone also exists in other color variants based on other elements. 
Cobalt and manganese can be substituted for copper; the resulting crystals have a more blue or silvery appearance and are suspended in a strongly-colored matrix of the corresponding ionic color, resulting in Blue Goldstone or Purple Goldstone respectively. Green Goldstone forms its reflective particles from chromium oxides rather than the elemental metals, but is otherwise fairly similar..
Black Agate (Onyx) which is truely a died black Agate, is more common and perhaps the most famous variety, but not as common as natural Onyx. Onyx is a crypyocrystalline form of Quartz. The colors of its bands range from white to almost every color (save some shades, such as purple or blue). Specimens of Onyx contain bands of colors of white, tan, and brown. As stated, the pure black form which most people know as Onyx, is not a naturally occuring variety. Black Agate or poorly colored Onyx is heated and dyed black to come up with the pure black form so well liked within the jewelry industry.
..
