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It tickles me that most of the gemstones in the crown, St. Edward's Crown, which will be used at Charles III's coronation, are not precious gemstones in today's usage. They would be emerald, ruby, sapphire and diamond. The crown includes rubies and sapphires. But no...

Lovers of purple gemstones (amethyst anyone?) will fall in love with this purple rock. Like lapis lazuli, a jewelry quality rock, charoite has an intense color, purple rather than cobalt blue, but it isn’t a gemstone. Rocks are two or...

Like granite, rhyolite is used for landscaping and ground fill. It’s not a good stone for construction however, so buildings would never be constructed of rhyolite as they are in granite. Some rhyolite is good for jewelry cabochons and beads. Rich in silicon, it is often glassy and either fine grained or containing larger crystals.

Peridot is a gem quality olivine that is always olive green, varying in shade from yellow green to an intense green to a brownish or muddied green due to the amount of iron a given sample contains. That middle green color is most sought after, as are larger gem quality stones. Large peridot is rare and costly.

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Fossil coral isn’t an endangered coral. In the gemstone industry they have shortened agatized fossil coral to fossil coral. Price alone tells you it’s not something that comes from a threatened species. It is coral in a way, but ancient coral, found in the ground after being inundated by silt or something else, not an expert here, some 20 million years ago. Agate replaced the coral. So it's no longer coral.

Caribbean-blue waters lapping the sunny island shores find their duplicate in a unique stone found only in the Dominican Republic. Larimar is a light blue type of pectolite, a stone that comes in other colors and from other parts of the world. But most pectolite is not amenable to cutting for jewelry. 

Adularescence or schiller as it is commonly called creates a cat's eye when the band is clearly distinct and a silky luster of chatoyance when the band is indistinct.

Ruby in fuchsite is a pretty combination gemstone with ruby scattered through it. Although not all fuchsite has ruby in it. When it does, it's pretty amazing. 

Amber comes in a variety of colors ranging from bone white to black.