Why do stones have different colours

What Are Rocks Used For? How big can a boulder get? What is a cobble? How tiny can a rock be? Why are rocks different sizes? How many rocks are in the whole world? Boulders are the biggest type of rock, to be found on a mountain. A boulder is so big that most humans can't move them on their own. These phenomena are related to the structural features of mineral formations regular alternation of phases of different composition in iridescent labradorites and peristerites and in sunstone [aventurine feldspar] and moonstone; the globular structure of opals or to the structure of the surface layer of crystals various types of tarnish, such as the iridiscent film on bornite, chalcopyrite, pyrite, and covellite.

The study of the color of minerals provides information about the crystallochemical and genetic characteristics of minerals and is useful in the synthesis of high-quality analogs of natural gems. Reference: Marfunin, A. Vvedenie v fiziku mineralov. Moscow, Platonov, A. Priroda okraski mineralov. Kiev, Sunday, November 14, Sign in. Forgot your password? Get help. Password recovery. It's for this reason that rubies are found in the red color spectrum, from dark pink to deep purple.

Ruby is the July birthstone, and it signifies the 15th and 40th anniversaries. Ruby red is the color of love, so this precious stone is understood to represent purity and passion. Rubies are given a 9 on the Mohs hardness scale, making them almost as hard as diamonds, and thus very suitable for engagement rings.

As one of the most well-known precious gemstones, sapphire is a beloved choice for an alternative engagement ring —partially because of its history in pop culture. Royal wearers like Princess Diana and Kate Middleton made blue sapphires mainstream.

But although it's most often associated as a blue gemstone, sapphires are much more diverse than that. Sapphires belong to the corundum family, and they come in just about every gemstone color, including pink, orange, yellow, purple and black. They even come in colorless or white gemstones, making them an alternative to a traditional diamond.

Different varieties also have various finishes, like a star sapphire—this form includes intersecting needle-like inclusions in a star pattern on the face of the stone.

The September birthstone is sapphire, and it represents the fifth and 45th wedding anniversaries. Unsurprisingly, sapphire is associated with royalty. It's believed to attract abundance and gifts while repelling negative energy.

Sapphire is relatively hard—it's a 9 on the Mohs hardness scale, making it very comparable to the strength of a diamond. A crystal variety, spinel is a gemstone available in a number of colors. Spinel is often confused for ruby because it's commonly available in a similar deep red hue. But red isn't the only option—spinel crystals can be found in pink, blue, purple, brown, black and green gems.

Although it's a relatively new addition, spinel is considered to be a secondary birthstone for August. Some say that spinel promotes feelings of hope and revitalization, as it's a stone that represents joy and having zest for life. Spinel tends to fall between 7. Only found in Tanzania near Mount Kilimanjaro, tanzanite is a blue and purple variety of the mineral zoisite.

Not to be confused with sapphire, tanzanite also comes in a deep blue hue. Beyond this, the rare gemstone can also be found in shades of purple and red. Tanzanite is known as a secondary December birthstone. Thanks to its vivid blue colors and high clarity, there's potential to opt for a tanzanite gem with a high carat weight.

While its true meanings vary, tanzanite gems—which are rarer than diamonds—are believed to represent new beginnings and prosperity. Tanzanite is rated 6. Since it's a softer gem, look for tanzanite engagement rings with low, protective settings. Known for its earthy, brownish tint, topaz is a silicate mineral. Although common topaz is colorless, it also comes in a natural pale yellow hue.

Topaz can also be treated to come in shades of blue, green, yellow, orange, red, pink and purple. A special variation—known as imperial topaz—comes in a fiery, golden red color. Like citrine, Topaz is the November birthstone. Blue topaz also represents the fourth wedding anniversary. Topaz has long been associated with fiery energy and is thought to represent love, passion and purpose. Topaz has an 8 rating on the Mohs hardness scale, making it suitable for daily wear. If the phrase "watermelon sugar" was a gemstone, it would be tourmaline.

This crystalline mineral is quickly rising as a popular wedding ring gemstone thanks to its playful, colorful hues associated with watermelon think: greens and pinks. The composition of each individual tourmaline gem impacts its appearance. Some tourmaline stones can have a greenish-blue look, while others skew more yellow. Alternatively, some tourmaline gems can be significantly pinker, with red and purple undertones.

Paraiba Tourmaline is a special variety that comes in bold neon blue and green hues. With strong grounding forces, tourmaline is thought to offer powerful healing and protection powers. Generally, tourmaline gemstones tend to fall between 7 and 7. Main Menu. Sign Up. Back to Main Menu. Planning Tools.

Wedding Vision. Discover Your Vision. Take The Knot's Style Quiz. Reception Venues. Cordierite , the most famous dichroic mineral is bluish-purple, but turns gray when rotated or viewed at a different angle.

The properties of opalescence , labradorescence , and dichroism , as well as other optical properties are explained in greater detail in the section " Other Properties ". Mineral colors may be artificially enhanced in various ways, especially when they are used as gemstones. This includes heating and irradiation both previously mentioned , as well as dying. A few minerals, especially Agate , are sometimes dyed to enhance their color. Color alone will not normally identify a mineral, but it can be a very helpful factor.

Many minerals come in a diversity of colors, and many different minerals have similar colors. However, a few minerals can be identified solely by their color usually in addition to crystal shape , for example Azurite , Rhodochrosite , and Dioptase. Such minerals are known as monochromatic minerals. Together with color, a crystal shape can identify most of the better known minerals. It is best to observe the mineral in good lighting, preferably daylight. Make sure not to observe a tarnis hed or discolored surface.

View All Videos View Minerals.