Properties and variety of colors of corundum stone

Mineralogists, chemists, mechanical engineers, electronics engineers - they all know the mineral corundum. But among jewelers it did not gain popularity on its own. In jewelry, its valuable varieties are much more important.

Corundum deposits

As a hypogene mineral, corundum is common in igneous rocks that are poor in silica (syenites, nepheline syenites).
Large crystals are also found in pegmatites. Crystals about 10 cm in diameter are found in metamorphic rocks such as gneisses, garnet amphibolites, and granulites. Precious varieties of corundum are found in placers. — Advertising —

Corundum deposits are located in India, Sri Lanka, Madagascar, Burma, Thailand, Greece, Canada, Norway, the USA and Russia.

History of corundum

Corundum is an oxide of aluminum and is also known as alumina because it is a constituent of clay.
Depending on the structure of the crystal lattice of the mineral, today many of its subspecies are distinguished. In metal processing and polishing, corundum called emery has been used for several thousand years. In mechanical engineering, so-called corundum-based sapphire glasses are widely used, when the part must be both transparent and stable. And in the jewelry environment, sapphires and rubies – colored varieties of corundum – have been known for a long time.

Colors and varieties

Corundum is a mineral found in nature in a large number of shades:

1. Blue: if corundum has this color range, then it contains titanium, and such a stone is called sapphire. The more of this chemical element a gem contains, the brighter its shade. The dark blue stone is called indigo sapphire. The most valuable, from the point of view of jewelry, is the Ceylon sapphire.
2. Red: This variety of corundum is called ruby, and the stone contains chromium oxide. The most valuable crystals are those that have a fiery color and a purple tint. If the color of a mineral contains shades of brown, then its value decreases.
3. Yellow: This mineral is a Padparadscha sapphire. It contains iron oxide and nickel, which give it this shade.
4. Brown: The combination of large amounts of titanium and iron oxide gives corundum a rich brown color. In the jewelry industry, such a stone is not in high demand.
5. Grey: An opaque, colorless stone of little value. Used only in industrial production.
6. White: does not contain impurities of other chemical elements, which explains its colorlessness. White corundum is a valuable raw material for the production of glass and abrasives.

Any corundum may become discolored when exposed to intense sunlight.

Physico-chemical characteristics of corundum

Corundum crystals are barrel-shaped, dipyramidal and tabular in shape, pseudohexagonal, found in the form of single formations, various intergrowths and aggregates.
They have imaginary cleavage, hardness on the Mohs scale of 9, and a specific gravity of 3.9-4 g/cm³. The melting point of corundum is 2050 °C. — Advertising —

The color range starts from colorless crystals and varies to shades of gray, red, blue and purple. The crystals have a glassy or matte luster. If there are inclusions of thin rutile needles, asterism appears in them.

Chemically, corundum is very stable and does not dissolve even in acids.

Fake diamond

An artificial mineral is obtained by treating alumina at high temperatures in laboratory conditions. Using the Verneuil method, stones are obtained that are characterized by curvilinear zoning, due to which such crystals acquire an attractive appearance. Artificial corundum is also produced using the hydrothermal method, which requires all the chemical elements that natural stones are made of.

Jewelry with sapphires

The composition is sent to special ovens (autoclaves) and the temperature is set to 1000 degrees. During crystal growth, the temperature is adjusted to the required values. Hydrothermal sapphires and corundums are stones with a rich color, the crystals of which are free of any cracks or defects. Inclusions in the form of air bubbles may occur inside hydrothermal corundum.

Such stones are in demand in the jewelry industry, since jewelry with these gems has an affordable price. Thus, 1 carat of high quality ruby ​​(sapphire) mined from nature is estimated at 400 dollars or more. Hydrothermal gems are several times cheaper, so jewelry with them is available to many buyers.

Only an experienced gemologist can distinguish natural sapphire from hydrothermal sapphire. If a buyer finds jewelry with a sapphire or ruby ​​in a jewelry store, and the gem in it is labeled as hydrothermal, then the stone is considered synthetic, or artificial. In the case when this gem is offered as natural, we are talking about a fake.

Types of corundum

The following varieties of corundum are known depending on color:

• Rubies or “red yachts”, red precious stones of the first category, transparent samples are valued even more than diamonds. Star rubies have an asterism effect.

• Sapphires or “blue yachts” are distinguished by a variety of colors from pale blue to deep blue.

• Green corundums or oriental emeralds

• Violet corundums or oriental amethysts.

• Padparadschi are yellow or orange-yellow corundums.

• Leucosapphires or oriental diamonds are colorless and completely transparent corundums.

The magical properties of corundum

Even in ancient times, people paid attention to the magical properties of corundum.
This active stone helps everyone who strives to achieve high goals. For this reason, it is not recommended for lazy people and can even harm them. Corundum awakens a person’s inner potential, directs the thoughts and aspirations of the owner in the necessary direction with appropriate efforts and interests. It eliminates fears and self-doubt before starting a new business, and destroys all obstacles. Corundum is recommended for anyone involved in mental work, such as students and scientists. It is interesting that corundum interacts very closely with its owner and exchanges energy with him.

The effect of corundum on a person depends on its color and the place of contact with the body. Beads, pendants and necklaces with the mineral are a source of calm, eliminating irritability and fears. Corundum earrings help to find harmony and seem to whisper to a person what to do right. Rings with corundum help to reveal talents and stimulate the acquisition of new knowledge.

How to distinguish a fake?

Rubies and sapphires are precious stones, jewelry with which has a high value. For this reason, scammers may offer jewelry with fake gems to buyers, setting a high price for them. Only an experienced gemologist can give a reliable assessment of the authenticity of any stone, but there are methods that help you independently identify an outright fake of corundum:

1. A real sapphire (ruby) is a dense and weighty stone, while an artificial one can be light.
2. Due to its high hardness, corundum easily leaves scratches on glass, and this applies to both natural and laboratory-grown crystals.
3. Any mineral does not conduct heat, so it does not heat up from the heat of human hands.

If the price of a carat of jewelry corundum is several times lower than that of a natural stone, then the seller must clarify the origin of the gem. If it is hydrothermal sapphire (ruby), then it really has a more affordable price.

In order not to make a mistake when buying jewelry with corundum, you need to give preference to a reliable seller with an excellent reputation.

The healing properties of corundum

Corundum is a source of peace, it helps in the treatment of depression and nightmares, and even with serious mental disorders.
In addition, the mineral affects the functioning of the gastrointestinal tract and cardiovascular system, normalizes blood pressure and blood circulation. It is believed that the healing properties of corundum depend on its color. Thus, red minerals have the greatest effect on blood vessels and the heart. Blues are responsible for healthy vision. Violet helps with mental disorders.

Industries of application of corundum

Ordinary corundum is opaque, coarse- or fine-grained gray crystals. Large opaque crystals are also found. Such samples are used as an abrasive material, emery, or grinding disc due to their high hardness, and their high melting point makes it possible to make fire-resistant materials and enamels from them.

In modern production, corundum is also used as a substitute for glass, which is called sapphire. It is used in the manufacture of cameras and mobile phones.

Large crystals of unusual shape are popular among collectors. And in jewelry, the most popular colored varieties of corundum are sapphires and rubies, which are used as inserts in a wide variety of jewelry.

Application of stone

Transparent crystals with a glassy luster and intense color are in demand among jewelers. Corundum is cut into cabochons and facets. They work with the gem using diamond-coated tools. The processed stone is inlaid with jewelry made of precious metals.

Minerals are also used for industrial purposes:

• Sandpaper and abrasives are made from corundum powder;
• ruby is found in watch movements;
• corundum is a raw material necessary for the production of glass for portholes;
• Glass for gadgets is made from sapphire.

The high demand for corundum in industrial production is explained by the high hardness of the stone.

Ruby in gold

Corundum and zodiac sign

Corundum does not have a beneficial effect on all zodiac signs. His favorites are Cancer, Aquarius and Pisces, whom he helps and guides in the right direction. Corundum is highly not recommended for Aries and Capricorn men, as it has a negative effect on them. Only mature Aries women can wear jewelry with corundum without fear of the negative effects of the mineral.

Talismans and amulets

A talisman with corundum will give its owner protection from the negative influence of others. If you wear a stone on your chest, it will help protect you from negative emotions and unreasonable fears. Earrings with a stone will give a person prudence and insight. Wearing a ring with a sapphire or ruby ​​helps to reveal talents.

It is useful to carry a natural untreated stone with you, which is recommended to be protected from the eyes of others.

Corundums will enhance their energy if worn together with amethysts and garnets.

Interesting facts about corundum

• The British Museum houses an octagonal sapphire “rose”, weighing 31 carats, which belonged to Sir Hans Sloan. Corundum of this size is very rare.
• The most perfect in terms of aesthetic parameters is considered to be a pale blue sapphire with pyramidal processing, which is kept in a Dutch jewelry house. It was called the “blue princess”, and this specimen weighs 114 carats.
• The red variety of corundum, which is commonly known as ruby, has always been valued more than diamonds.