Which stone comes in different colors?

In this article we will talk about the color of precious and semi-precious stones and the reasons for its occurrence. The information provided about the factors influencing the observed color and its components will help when buying or selling natural cut specimens and will be useful when evaluating. You will also learn the main reasons that cause the appearance of additional shades in gems. And information about the influence of a specimen’s color on its value can help in understanding the structure of the precious stones market. In the photo: color varieties of the beryl mineral: aquamarine (blue), peachy pink morganite and golden yellow heliodor Color is the most important characteristic of any stone. Of all the quality parameters, it is the color that most strongly influences the overall attractiveness and cost of the gemstone. Color is also an important diagnostic feature when identifying gems. The quality of colored natural jewelry stones is assessed by gemstone specialists – gemologists.

The main reason for the appearance of color

In the photo: top red ruby, 4,06 carats, Burma The main reason for the appearance of color – the ability of a gemstone to selectively absorb light rays from the white light spectrum. The main components that shape a person’s perception of color are light, stone and the observer himself. White light contains all spectral components (i.e. all the colors of the rainbow). Each color corresponds to a specific wavelength. When the light reaches the stone, part of the spectrum of white light is absorbed, and the totality of the light waves passing through the stone returns to the eye of the observer and causes the sensation that he sees. If a gemstone completely absorbs all wavelengths, it will appear black. If it completely reflects (or transmits) light, then it is perceived by the observer as white or colorless. A stone that absorbs light only at certain wavelengths appears to be a specific color to the observer. Let’s look at this with an example. We perceive the color of a ruby ​​as red, because. The stone absorbs green, blue and violet rays from light, and transmits only red, orange and yellow ones. When the rays passing through the ruby ​​reach the eyes of the observer, the human brain combines them and interprets them as red.

The influence of lighting and external factors on the observed color of the stone

The influence of lighting and external factors on the observed color of a mineral can be quite significant. The type of lighting itself (its color temperature) has a great influence on the color of the sample visible to the observer. So fluorescent lamps (white light) emit more blue, violet and green rays, which enhance the corresponding colors in the stones. And incandescent light (yellow light) contains more red, orange and yellow rays, so stones of the same colors will look better under that light. So for this reason, when selling red rubies, sellers often light the display case with lamps that produce yellow light, while the display case with blue sapphires will be illuminated by fluorescent lamps (white light). This factor of visual color enhancement depending on the type of lighting must be taken into account when purchasing stones. The standard lighting for color assessment is gemological lamps with daylight (365 nm). On video: blue sapphire in different lighting. Incandescent light produces a purple tint

How to describe the color of a gemstone

• Color tone
• lightness
• saturation.

Color tone – a characteristic of color that determines its correspondence to pure spectral radiation. This is a visual impression. In this case, the main tone and an additional shade (for example, orange, yellowish-orange) are described. The most highly valued are colored jewelry stones, the color of which is as close as possible to the pure spectral color, without additional shades.

In the photo: zircons from Cambodia. The color of the upper specimens is valued approximately twice as much as the lower ones, because it is more saturated and not as light.

Lightness – a color characteristic due to the ability of a stone to absorb or reflect light radiation. It describes the position of a stone’s color on a scale from dark to light. If a stone intensively absorbs the light radiation incident on it, it looks dark; if it absorbs weakly and mainly reflects, it looks light. Example: The color may be described as dark greenish blue or medium greenish blue, light greenish blue.

Saturation – this is the strength or intensity of the perception of color tone, the brightness of the color. For example, “pale red” is a red of low saturation, and “bright red” is a red of high saturation.

Additional colors

Additional colors other than the base color may appear in some stones for various reasons. Let’s look at the main reasons that cause the appearance of additional colors:

• Color change effect
• Pleochroism
• Window
• Color zoning

Color change effect

Color change effect – an optical effect when two colors are observed in daylight and incandescent lamp light. The primary color is the one visible under a fluorescent lamp, and the secondary one under an incandescent lamp. The intensity of the color change is defined as weak, moderate and strong. Alexandrite has a color-changing effect, changing color from green (in daylight) to red (in incandescent light). This effect can also manifest itself in some garnets, spinels, corundums and other minerals.

In the photo: a garnet with a color changing effect under the daylight of a gemological lamp (left) and under the “yellow” light of a flashlight (right), 11,30 carats

Pleochroism

Pleochroism – the property of a transparent mineral in which a change in color can be seen depending on the direction of observation. The color of pleochroism is assessed if it is visible from the side of the stone platform. The intensity of pleochroism is assessed as weak, moderate and strong. Strong pleochroism is characteristic, for example, of tourmalines and tanzanites.

In the photo: observation of pleochroism colors in tanzanite through a special instrument – a dichroscope

In the photo: observation of pleochroism colors in faceted rubellite

Window

Window – an area of ​​pale color that may be located in the center of a cut sample if the correct proportions of the cut are not met. In this case, light “leaks” through the edges of the pavilion. Additional color is assessed if the size of the “window” is more than 50% relative to the area of ​​the stone. Instances with a large “window” do not look very attractive, and their cost is lower.

In the photo: due to the shallow depth of the pavilion, a pale “window” has formed in the center of the yellow sapphire.

Color zoning

Color zoning – This is an uneven distribution of color, noticeable when viewed through the surface of the stone. The stone can be specially cut so that when viewed from the site, areas of different colors are visible. This is typical, for example, for ametrines and polychrome tourmalines. But for many stones, the presence of color zoning, visible from the side of the stone platform in the form of alternating light and saturated areas, will be considered a disadvantage, and then it reduces the cost. Unevenness of color can be expressed in the form of spotting in sapphires, rubies, emeralds, etc.

In the photo: sapphire from Sri Lanka. If the sapphire were a uniform blue, it would cost more

In the photo: polychrome tourmaline from Mozambique. The presence of differently colored color zones in this stone does not reduce its value

In the video: polychrome tourmaline, correctly oriented color zoning from pink to green makes it more attractive

Effect of color on cost

The effect of color on beauty can be key when assessing the value of a gemstone. The more beautiful the stone, the more expensive it will be. Specimens of bright, saturated colors are the most highly prized. Very light or very dark stones are much cheaper. The presence of unwanted additional shades can reduce the cost several times compared to the cost of a stone that has a pure spectral tone. When purchasing, you should pay special attention to the uniformity of color distribution. For example, the price of a blue sapphire with a uniform color distribution can be 2 times higher than the price of a sapphire with noticeable zoning from the site side. Even the fashion for a particular color in a given season can influence the price. Stones of rare colors are valued higher than others, so in many cases the color they contain (tone, lightness, saturation) directly affects the price.

The price is also often influenced by the fact that the piece has been refined, that is, whether a particular stone has been treated to improve its color. In most cases, untreated specimens with completely natural colors are valued higher than heated ones, for example, blue sapphires. However, the cost does not always depend on the improvement. For example, the cost of tanzanites is not affected by heat treatment.

In the photo: sphenes from Madagascar weighing 25,17 and 22,18 carats. The color of the stone on the left is valued less because it has a more pronounced yellow tint and large dark areas are observed

You can get acquainted with stones of various colors in the Gem Lovers catalog.

Author of the article – Mikhail

In recent years, many precious stones have been subjected to various methods of refining, mainly to improve their color. For example, heat treatment or irradiation can turn unsightly stones into beautifully colored stones at low cost. The share of color-enhanced stones on the world market is growing year by year. At the same time, stones with bright, beautiful natural colors are becoming increasingly rare. Therefore, specimens whose color has been improved by refining can cost several times less than similar stones, but with a natural color.

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From this article you will learn which stones are red and pink.

In the photo: pink and red stones from the Gem Lovers collection (kunzite, rubellite, spinel)

Precious and “semi-precious” stones of red and pink colors have always been considered the most valuable and one of the most desirable. Since ancient times, the color red has been associated with love and passion; it also symbolizes power. Pink is the embodiment of tenderness, femininity, purity and romance. In this article we will look at a number of both well-known names and more rare ones.

Learn about the main cause of color in gemstones and the main components of stone color in our article on DK color.

Ruby

In the photo: untreated ruby ​​from Burma, 4,06 carats

Ruby is a gemstone, a type of corundum with a deep red color. Rubies can be colored with shades of pink, purple or orange. In the trade, the term Pigeon Blood may be used to denote the most valuable bright red color of a ruby. Some of the best colored rubies are mined in Myanmar (Burma). Burmese rubies are an established brand in the jewelry world. Untreated pigeon’s blood rubies from Burma are the most valuable. The best quality Burmese rubies can fetch over US$1 million per carat at auction. Today, rubies from Mozambique are found on the world market more often than others; their color can also be very beautiful, but they cost several times less than Burmese ones.

Spinel red and pink colors

In the photo: Burmese spinel weighing 12,46 carats

Spinel is a rare and beautiful mineral with a wide range of colors. Large gem-quality spinel is rare and therefore especially valuable. The high hardness of spinel (about 8 on the Mohs scale) allows it to be used in all types of jewelry. The most valuable is the bright red spinel. Over the past few years, the price of rich pink-red spinel from Tanzania has increased greatly. Spinel has been known as a gem since ancient times. Previously, red spinels could not be distinguished from similar-looking rubies and were valued equally highly. The imperial crowns of Russia, Great Britain, France and Germany are decorated with spinel.

Tourmaline rubellite

In the photo: rubellite tourmaline from Brazil, 15,03 carats

Rubellite is the name of a pink and red “semi-precious” stone, one of the most expensive varieties of the mineral tourmaline. Sometimes rubellites with a slight purple tint are found. From Latin the name of this stone (lat. rubellus) is translated as “reddish”. Rubellites often contain inclusions, so the approach to assessing their purity is not very strict, but their color is in the foreground. The brighter the rubellite, the more expensive it is. Rubellites are very popular today, and they can be found in the collections of many world jewelry brands.

Red grenades

In the photo: Tanzanian garnet weighing 11,71 carats

Garnet is a large group of minerals, including varieties of different colors. The most famous are red garnets. Pyrope is a “semi-precious” stone, its color ranges from fiery red to dark red, sometimes brownish. The name of the mineral is translated from Greek. “pyropos” – fire-like. In jewelry it is often represented in small specimens of a thick dark color. Almandine is a red garnet with a purple tint, less often dark brown. Its name is associated with the city of Alabanda in Asia Minor. Good quality specimens are more expensive than pyrope. Rhodolite is a commercial variety of garnet, chemically intermediate between pyrope and almandine. The name of this “semi-precious” stone comes from the Greek words “rhodos” (rose) and “lithos” (stone). Its color ranges from pink to pinkish-red, violet-red.

Pink sapphires

Pictured: unheated pink sapphire from Sri Lanka, 3,36 carats

Pink sapphire is a precious stone, bright transparent specimens of which are highly valued. Sapphires of this color are among the most expensive. Like ruby, this gem is a variety of corundum. In the world now there is no single clear understanding of where the color line lies between pink-red sapphires and rubies. The best pink sapphires come from deposits in Madagascar, Burma, Sri Lanka, Vietnam and Tanzania. If such sapphires also have an orangish tint, then they are called “Padparadscha.” The color of these rare and valuable sapphires has been compared to lotus and sunset petals. Pinkish-orange sapphires are mined in Sri Lanka, Madagascar and Tanzania.

morganite

In the photo: morganite from Brazil, 11,65 carats

Morganite is a jewelry variety of the mineral beryl. This gem is named after the banker and mineral collector John Morgan. Its second name is “vorobyovite”, given in honor of the Russian scientist V.I. Vorobyov, who first discovered this mineral in the Urals. The color of this gemstone is very rarely saturated; it is characterized by light shades of pink, orangish-pink, and peach. Orangeish hues reduce the cost of morganites. Some of the best morganite in the world comes from Brazil. It is also mined in Afghanistan, Madagascar, Namibia and Mozambique. Morganite is used in their products by such famous brands as Van Cleef & Arpels, Louis Vuitton, Dior and Tiffany & Co., which “promoted” this gem on the international stage.

What other stones can be red and pink?

Very expensive topazes, which are occasionally found in deposits in Brazil and Pakistan, can also have a pink color. These topazes may be called imperial topazes and usually have an orange component. Kunzites are much more common; they also have a pinkish color, but often with a purple tint. Less valuable gems include rose quartz, which is mined in Brazil and Madagascar. Of the rarest semi-precious stones, pezzottaite has rich pink tones, which often contains inclusions and cracks. Among the opaque ornamental stones with this color, rhodonite and rhodochrosite can be distinguished. The most expensive gemstone, which can be pink or red in color, is a diamond. The cost of red cut diamonds these days at auctions can exceed $2 million per carat.

You can get acquainted with stones of various colors in the Gem Lovers catalog.