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The Difference Between White Corundum And Single Crystal Corundum

White Corundum

Corundum is a crystalline form of aluminum oxide (Al₂O₃) and is known for its hardness, making it suitable for a variety of applications, especially as an abrasive. Both white corundum and single crystal corundum are types of corundum, but they have distinct differences in their structure and properties:

Property White corundum Single crystal corundum
Origin Natural Synthetic
Color White or translucent Can be any color, but is typically colorless or blue
Crystal structure Polycrystalline Single crystal
Strength High Very high
Hardness High Very high
Optical transparency Translucent to opaque Transparent

Formation & Structure

White Corundum: This is formed by the fusion and crystallization of high-quality alumina. The resultant product is cooled, crushed, and then fused again. Its structure consists of irregularly shaped particles that make it sharp and hard.

Single Crystal Corundum: As the name suggests, single crystal corundum is made up of individual single crystals. This type of corundum is produced by slowly cooling high-purity molten alumina at controlled rates. This slow cooling allows for the formation of larger individual crystals as opposed to the polycrystalline structure seen in white corundum.

Single Crystal Corundum
Single Crystal Corundum / Monocrystalline Alumina


White Corundum: It is translucent or opaque and is typically white, as its name suggests.

Single Crystal Corundum: It tends to be transparent to translucent and can be found in a variety of colors or can be colorless.

Hardness & Toughness

White Corundum: It is very hard (9 on the Mohs scale) but less tough than single crystal corundum. Due to its polycrystalline nature, it can fragment more easily.

Single Crystal Corundum: It is also very hard (9 on the Mohs scale) but is typically tougher than white corundum due to its single crystalline nature.


Single crystal corundum is used in a variety of applications, including:

  • Optical windows and lenses
  • Laser crystals
  • Substrates for electronic devices
  • Wear-resistant coatings
  • Medical implants

White corundum is also used in a variety of applications, but it is typically used in less demanding applications than single crystal corundum. Some common uses of white corundum include:

  • Abrasives
  • Refractories
  • Ceramic products
  • Water filters


Generally, single crystal corundum, especially of gemstone quality, tends to be more expensive than white corundum because of its rarity, beauty, and the specific conditions required for its formation.

It’s important to note that the specific properties of corundum, whether white or single crystal, can vary based on the specific conditions under which they were formed, including impurities present, cooling rates, and other factors.

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