corundum
noun
co·run·dum
kə-ˈrən-dəm 
: a very hard mineral that consists of aluminum oxide occurring in massive and crystalline forms, that can be synthesized, and that is used for gemstones (such as ruby and sapphire) and as an abrasive
Examples of corundum in a Sentence
Recent Examples on the Web
Rubies are mainly made up of the mineral corundum, which is composed of the elements aluminum and oxygen in a regular, repeating array.
—
Daniel Freedman, The Conversation, 4 Feb. 2025
The chromium replaces about 1% of the aluminum in the corundum or beryl crystal when a ruby or emerald forms underground at a high temperature and pressure.
—Daniel Freedman, The Conversation, 4 Feb. 2025
The color pink inspired the second Streamliner Cylindrical Tourbillon Skeleton which utilizes not just a pink rubber strap, but also a dynamic piece of pink synthetic corundum within the dial.
—Blake Buettner, Robb Report, 8 May 2024
The domed disc is a pink synthetic corundum in the same vein as ruby or sapphire, and the result is a soft, translucent pink that shifts not only depending on viewing angle and lighting.
—Blake Buettner, Robb Report, 8 May 2024
At $950, the luxury wearable is made from black synthetic corundum with 18-karat yellow gold braided torchon detailing and a signature interlocking G logo.
—Sara Klausing, Men's Health, 4 Nov. 2022
According to a new study, the night side is cold enough to form metal clouds of iron and corundum.
—Joshua Hawkins, BGR, 25 Feb. 2022
The temperature differences between the two sides of the planet also mean that the nightside is cool enough for metal clouds made of iron and corundum to form.
—Ashley Strickland, CNN, 21 Feb. 2022
Known for their red color, rubies are part of the corundum family of gemstones, which are gems that are compact and dense, according to the International Gem Society.
—Jordan Mendoza, USA TODAY, 27 Oct. 2021
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Daniel Freedman, The Conversation, 4 Feb. 2025
The chromium replaces about 1% of the aluminum in the corundum or beryl crystal when a ruby or emerald forms underground at a high temperature and pressure.
—Daniel Freedman, The Conversation, 4 Feb. 2025
The color pink inspired the second Streamliner Cylindrical Tourbillon Skeleton which utilizes not just a pink rubber strap, but also a dynamic piece of pink synthetic corundum within the dial.
—Blake Buettner, Robb Report, 8 May 2024
The domed disc is a pink synthetic corundum in the same vein as ruby or sapphire, and the result is a soft, translucent pink that shifts not only depending on viewing angle and lighting.
—Blake Buettner, Robb Report, 8 May 2024
At $950, the luxury wearable is made from black synthetic corundum with 18-karat yellow gold braided torchon detailing and a signature interlocking G logo.
—Sara Klausing, Men's Health, 4 Nov. 2022
According to a new study, the night side is cold enough to form metal clouds of iron and corundum.
—Joshua Hawkins, BGR, 25 Feb. 2022
The temperature differences between the two sides of the planet also mean that the nightside is cool enough for metal clouds made of iron and corundum to form.
—Ashley Strickland, CNN, 21 Feb. 2022
Known for their red color, rubies are part of the corundum family of gemstones, which are gems that are compact and dense, according to the International Gem Society.
—Jordan Mendoza, USA TODAY, 27 Oct. 2021
Cite this Entry
“Corundum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/corundum. Accessed 30 Jun. 2025.
Copy CitationKids Definition
corundum
noun
co·run·dum
kə-ˈrən-dəm
: a very hard mineral of aluminum oxide used for grinding, smoothing, or polishing or in some crystalline forms as a gem (as ruby or sapphire)
Medical Definition
corundum
noun
co·run·dum
kə-ˈrən-dəm
: a very hard mineral Al2O3 that consists of alumina occurring in massive form and as variously colored crystals which include the ruby and sapphire
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