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April: Diamond
April's birthstone is the diamond.
Origins
The Earth's crust is less than 40 km thick, which is where rubies, sapphires, and emeralds form. To find diamonds, you have to go much deeper: about 200 km towards the Earth's center. Scientists measure pressure in pascals, and where diamonds form, the pressure is 5 to 6 gigapascals, equivalent to 80 elephants on your big toe.
All gemstones are formed from a combination of elements; the diamond is formed from only one: carbon. It is the result of crystallization that requires an enormous amount of time and energy: literally over 1000 degrees Celsius under a pressure of 75 tons per cm². Each carbon atom bonds with four others to form a pyramid with four equal equilateral triangles as faces.
All diamonds found on the Earth's surface were formed between 1.5 and 3.5 billion years ago, which is between 25 and 75% of the Earth's age. The oldest ones that could be dated predate life on Earth.
More than 25 million years ago, diamonds rose to the surface through the force of rare and violent volcanic rock explosions, kimberlite. Under the action of erosion and weathering, kimberlite releases the crystals from their surrounding matrix. Runoff then carries them to riverbeds, rivers, and the sea, where they mix with masses of sediment.
In the most seismic regions, diamonds evaporated, but in more stable ones, they survived. They went unnoticed for millions of years before their deposits were discovered and exploited...
So they went unnoticed for millions of years, before their deposits were discovered and exploited. This new chapter of their history begins in India, over 3,000 years ago…
The very first references to diamonds are found there, in Buddhist manuscripts dating back to 400 BC. At that time, they were used to adorn religious objects, and were attributed magical and protective powers.
Until the early 18th century, India was the world's only source of diamonds! Three main areas existed, and the most famous of them was Golconda (the name of the city around which the deposits were located).
Jean-Baptiste Tavernier, a traveler, merchant, and expert in stones, was one of the first to go there and made the Golconda deposits in India famous, notably with the blue diamond purchased by Louis XIV, which became the French Crown's blue diamond.
Even today, Golconda diamonds fascinate collectors and jewelry enthusiasts: some of the clearest and most perfect in the world are said to have been extracted there since the 1720s before its complete depletion around 1948. Many famous diamonds known for their incredible quality come from these mines.
The diamond trade from antiquity to modern times thus exhausted Indian deposits. Then, Brazilian deposits were discovered and supplied the Western market until the end of the 19th century, when South African deposits were found. Africa became the major exporter in the 20th century, followed by a market explosion. Today, Russia (where the first diamond was discovered in 1829) is the largest producer in the world, followed by Botswana, Canada, and Australia (which is also the only known significant source of pink diamonds).
Main characteristics
It has its own unit of weight: it is measured in Carats. This was set by convention in 1907, establishing that 1 carat is equivalent to 0.20 grams, or 5 carats for 1 gram.
This unit of measure is more precise than grams for measuring the weight of gemstones, especially diamonds. Be careful not to confuse the definition of carat used in jewelry for gemstones with that used in goldsmithing to assess the purity of gold.
The word carat originates from the Arabic word Qirat, the carob seed which served as a weight reference in antiquity for weighing gems. The tree seeds served as a reference standard in the Arab, Greek, and Roman worlds.
When looking at a diamond, the first thing one sees is its geometric shape (round, oval, pear, heart, etc.) but its weight is not visible to the eye; it is its volume (its dimensions) that is seen.
The price is always calculated based on the carat weight of the stone; diamond dealers use the Rapaport price list to calculate the price.
The price grids are classified by weight, and each table corresponds to a price for a weight range. The value of a diamond is not proportional to its weight. Similarly, the value of a 2-carat diamond is not equal to the value of two 1-carat diamonds.
Note that dimensions in millimeters are not proportional to its carat weight.
- A 0.25 carat diamond has a diameter of 4.10 mm.
- A 0.50 carat diamond has a diameter of 5.20 mm.
- A 1.00 carat diamond has a diameter of 6.50 mm.
Here is the carat weight and their dimensions in millimeters:
There are 4 quality criteria for diamonds, the "4Cs", used worldwide: Carat, Color, Clarity, Cut.
Only 30% of extracted diamonds are used for jewelry; the rest are used in industry due to their properties.
It has a hardness of 10 on the Mohs scale, which ranges from 1 to 10.
Overview of birthstones by month
January: Garnet
February: Amethyst
March: Aquamarine
April: Diamond
June: Alexandrite or Pearl
July: Ruby
August: Peridot
September: Sapphire
October: Tourmaline
November: Citrine
December: Tanzanite
