What is the differences between gems and crystals
Introduction
Gems and crystals – though often used interchangeably in informal contexts, scientifically these terms have some key differences. In this guide, we will understand what gems and crystals are, their similarities and differences, and provide tips for identification.
Definitions Gems Gems are defined as mineral crystals or organic materials that have been carved and polished for usage in jewelry and ornamental purposes. The key characteristics of gems are beauty, durability and rarity. Some examples of gemstones are diamonds, rubies, emeralds and sapphires. Gems possess properties like exceptional shine, high refractive indexes, hardness, color patterns, transparency and resistance to chemicals/acids that make them suitable to be used in jewelry.
Crystals Crystals are solids whose constituent atoms, molecules or ions are arranged in an repeating, orderly pattern extending in all three spatial dimensions. Almost all gems fit into this criteria of crystals. However, not all crystals can be classified as gems if they do not possess characteristics like beauty, durability or rarity. Some examples of crystals not used as gems are ordinary salt, snow flakes and vitamin C crystals.
Similarities between Gems and Crystals
Gems fit into the definition criteria of crystals – both have orderly atomic structure and identifiable shapes/facets.
Many gems like diamonds and emeralds have ‘crystal’ as a descriptor in their names, indicating their crystalline structure.
Both gems and crystals can occur naturally or be manufactured synthetically. Natural gems form inside Earth’s crust similar to other crystals.
Differences between Gems and Crystals
Purpose
Gems are used only for ornamental purposes in jewelry or collections because of attributes like beauty and monetary value. Crystals may have decorative, industrial, medical or technological applications.
Attributes
Gems necessarily need to exhibit hardness, brilliance, chemical resistance – properties valued in gemstones. Crystals may not possess attributes like shine or durability
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Composition
Gems are composed only of minerals or compounds like oxides, silicates and carbonates. Crystals can be composed of any solidifying compound including salts, metals and organics.
Structure
The atomic structure of gems lend to development of smooth facets and edges over time inside Earth’s crust. Shape may not be defined for compounds crystallizing in a laboratory.
Identifying Gems versus Other Crystals Hardness Test Check material hardness on the Mohs scale – genuine gemstones will fall within expected range (Diamond – 10, Ruby – 9, Topaz – 8). Other crystals will differ in hardness.
Clarity High quality gemstones are transparent or translucent. Opaque crystals indicate presence of impurities.
Refractive Index Measured by how much a ray of light bends when passing through the material. Each gemstone has a known range that can help distinguish it from crystals of other compounds.
Density Test The specific gravity of a gemstone can indicate if it is genuine or an alternative compound. Measured in g/cm3.
Thermal Conductivity Gems conduct heat at different rates – can be checked with thermal conductivity meters to identify gem type or authenticate.
Magnification Examining inclusions inside the material under 10x magnification can reveal identifying features or determine if it is synthetic.
Fluorescence Many gems like diamonds glow under ultra-violet light. Distinct colors emitted can help identify gemstone.
Chemical Resistance Gems are not altered or damaged when exposed to acids/alkalis. Crystals may dissolve, discolor or breakdown.
Spectroscopic Analysis Spectrometers analyze how matter interacts with electro-magnetic radiation. The spectral signature obtained is matchable to known gems to identify composition.
Conclusion
While gems fit the criteria for crystals due to their ordered internal arrangement, they differ from other crystals in being rare materials chosen for ornamental usage because of attributes like beauty and monetary value. By going through tests like density, hardness, magnification and thermal/chemical resistance, we can distinguish between a gem and other crystalline forms. Spectroscopic techniques can conclusively identify the specific gemstone based on spectral signatures.
