Have you ever seen a glittering diamond? If so, then you know the smile it brings to the face of admirers. This isn’t just true of diamonds; gemstones like emeralds, rubies and sapphires are all stones of different colors known for their brilliance and high prices. However, Mother Earth has provided us with many more jewels that are just as beautiful as those more famous varieties! This article will explore a few of these somewhat unknown beauties.
Before moving on, we should clarify the concept of carats. The purity and mass of gemstones and pearls are measured in a unit called carats. A carat is a unit of mass equivalent to 200 milligrams (0.2 grams) of the substance being measured. There are four basic parameters that govern the grading of all gemstones, commonly known as the four Cs of Connoisseurship: colour, clarity, cut and carat weight.
1. Blue Diamond: the most expensive gemstone
This article would be incomplete without the mention of the most expensive gemstone in the world. Yes, you heard that right… the most costly stone on the planet! A blue diamond is quite similar to a regular diamond, except for the additional element of color (blue) that leaves its observers spellbound. The gemstone owes this color to the small quantity of Boron present in its lattice structure. The Oppenheimer Blue became the most expensive jewel (per carat) ever sold at an auction in 2016. The 14.62-carat diamond cost its mystery buyer a whopping $50.6 million ($3.93 million per carat)
The Hope Diamond is another famous gemstone in this color category. First mined in India in the late 16th century, this rare stone travelled around the world before finally coming to rest in the National Museum of Natural History, USA.
Reference – Smithsonian Institution
The tourmaline family of gemstones consists of crystals that have a structure made of aluminium boron silicate (AlBoSio3). Within their core structure, metals such as manganese, iron, chromium and sodium are found, which impart the stones with various colors. Tourmaline stones come in many types, but watermelon tourmalines are perhaps the most interesting. The picture below quite clearly demonstrates where the name comes from!
Tourmalines are generally found among solidified deposits of molten magma near the veins that run closest to the core of the volcano and therefore experienced the highest temperatures. Another fun fact about these rare stones is that they might be magnetic. High concentrations of iron and manganese impart magnetic properties to some members of the tourmaline family. Now that’s what we call a multipurpose rock!
Reference – International Gem Society
3. Painite: the rarest gemstone
Most gemologists in the world agree that Painite is the rarest gem-quality stone found on our planet. First discovered in 1951 in a small mine in the Mogok region of Burma, only two such stones existed until late 2014. Chemically, this mineral is a borate of calcium, zirconium and aluminium with a chemical formula of CaZrAl9O15(BO3). It also contains trace amounts of chromium and vanadium, which are responsible for Painite’s typically orange-red to brownish-red colour.
Reference – Caltech
4. Red Beryl or Bixbite
Red Beryl is one of the most valuable gemstones in the world. For those whose favourite colour is red, this might be the most appealing gemstone on the list. This mineral is composed of beryllium aluminium cyclosilicate and falls under the category of emeralds. The red colour comes from manganese. First discovered in 1905 in Utah (United States Of America), Beryl is a known carcinogenic that can also lead to pneumonitis. Therefore, it needs to be handled with care. For every 150,000 gem-quality diamonds, there is just one gem-quality Red Beryl… that’s how rare these little glittering beauties are!
Reference – Emporia State University
5. Black Opal
We all know what an opal is, but a black opal is quite different in its color, form and characteristics. This article would be incomplete without mentioning the following two stones. The Aurora Australis, a 180-carat black opal, is the most valuable black opal in the world. Found in 1938 at Lightning Ridge, this amazing gemstone was valued around $763,000 in 2005.
Most readers will have heard of Halley’s Comet. It is a short-period comet visible from Earth every 75-76 years and is named after English astronomer Edmond Halley. Well, Edmond Halley not only had a comet named after him, but also a shiny piece of colored stone. A massive black opal was found at Lightning Ridge around the same time that the actual Halley’s Comet appeared in the Australian skies. Thus, the stone was named Halley’s Comet. It holds the Guinness world record for being the largest uncut piece of black opal in the world
Reference – International Colored Gemstone Association
Fluorite has an extremely simple chemical formula—Calcium fluoride (CaF2)—but can make even the most expensive gemstones look boring beside it. The best thing about these stones is that they’ve found in shapes of perfect isometric octahedrons that are visually stunning to observe. A crystal’s color is dictated by the way light interacts with the ions and chemicals in its lattice structure. The vibrant colors of fluorite result from the defects in its crystal lattice. Electrons that occupy the defective positions absorb the irradiating light and emit it in various colors. Unlike the other stones on this list, Fluorite is a relatively common mineral and occurs in vein deposits within rocks where water at very high temperatures used to flow.
Reference – Minerals.net
7. Benitoite: State Gem of California
Benitoite is also known as the State Gem of California, as it was first discovered from a single limited deposit in California in 1907, which remained the only source of this rare gemstone for a long time. Over the decades, a few more mines were found in Japan, Australia and Arkansas, but the output of gem-quality Benitoite is incredibly limited, which makes this mineral so rare that a pure carat of it will cost upwards of $10,000.