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Azure Asterism

Short answer: Sapphire is gem corundum, aluminum oxide, in any color except red, which is called ruby. Blue sapphire gets its color from iron and titanium, and sapphires also come in pink, yellow, green and colorless forms.

Some sapphires show asterism, a six-rayed star caused by light reflecting off needle-like rutile inclusions. The Star of India is a 563-carat grayish-blue star sapphire held by the American Museum of Natural History in New York, and it is unusual for being nearly free of flaws. The footage shows blue and fancy sapphires and the Star of India, with the presenter.

VideoWrite-up2 sources
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What should you know about Azure Asterism?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Sapphire is gem corundum.

    DD-166-F01 · Write-up · Exhibit A (Corundum)

  2. Iron and titanium make it blue.

    DD-166-F02 · Write-up · Exhibit B (Iron and titanium)

Video transcript: Azure Asterism: Needle Inclusions Give Star Sapphires Their Star

Sapphires like diamonds belong to the corundum mineral family and are primarily composed of aluminum oxide. DID YOU KNOW? What distinguishes sapphires is their vibrant range of colors with blue being the most well-known. However, sapphires can also be found in various hues such as pink, yellow, green, and even colorless. One of the most famous sapphires is the Star of India which is a massive nearly flawless blue sapphire. This gem exhibits a unique asterism a star-like pattern that emerges when light reflects off needle-like inclusions in the stone. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 30.0s Reel ·

Video coming soonAzure Asterism · Instagram Reel
Azure Asterism: Needle Inclusions Give Star Sapphires Their Star Instagram Reel · · 30.0s

The write-up

Needle inclusions give star sapphires their star. The Star of India weighs about 563 carats.

  1. Exhibit A

    Corundum

    Sapphire is gem corundum.

  2. Exhibit B

    Iron and titanium

    Iron and titanium make it blue.

  3. Exhibit C

    Many colors

    Sapphires come in many colors.

  4. Exhibit D

    Asterism

    Rutile needles make a six-rayed star.

  5. Exhibit E

    Star of India

    The Star of India is 563 carats.

Questions people ask about Azure Asterism

What mineral is sapphire?

Aluminum oxide.

Source: Write-up · Exhibit A (Corundum) · Wikipedia: Sapphire

What is red corundum called?

Not sapphire.

Source: Write-up · Exhibit B (Iron and titanium) · Wikipedia: Sapphire

What makes blue sapphire blue?

Trace elements.

Source: Write-up · Exhibit C (Many colors) · Wikipedia: Sapphire

What causes asterism?

Rutile needles.

Source: Write-up · Exhibit D (Asterism) · Wikipedia: Sapphire

Where is the Star of India?

In New York.

Source: Write-up · Exhibit E (Star of India) · Wikipedia: Star of India (gem)

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What mineral is sapphire?

    1. Corundum
    2. Diamond
    3. Beryl
    4. Quartz
    Show the answer

    Answer: A. Corundum Aluminum oxide. Source: Write-up · Exhibit A (Corundum) · Wikipedia: Sapphire

  2. What is red corundum called?

    1. Ruby
    2. Garnet
    3. Emerald
    4. Opal
    Show the answer

    Answer: A. Ruby Not sapphire. Source: Write-up · Exhibit B (Iron and titanium) · Wikipedia: Sapphire

  3. What makes blue sapphire blue?

    1. Iron and titanium
    2. Chromium
    3. Copper
    4. Gold
    Show the answer

    Answer: A. Iron and titanium Trace elements. Source: Write-up · Exhibit C (Many colors) · Wikipedia: Sapphire

  4. What causes asterism?

    1. Needle-like inclusions
    2. Paint
    3. Cracks only
    4. Heat
    Show the answer

    Answer: A. Needle-like inclusions Rutile needles. Source: Write-up · Exhibit D (Asterism) · Wikipedia: Sapphire

  5. Where is the Star of India?

    1. American Museum of Natural History
    2. The Louvre
    3. The Tower of London
    4. The Smithsonian
    Show the answer

    Answer: A. American Museum of Natural History In New York. Source: Write-up · Exhibit E (Star of India) · Wikipedia: Star of India (gem)

Cite this case file

Easterling, Marcus. "Azure Asterism." The Detail Department (DetailEnjoyer), case file DD-166, last updated Jan 7, 2024. https://detailenjoyer.com/case/azure-asterism/

Permalink: https://detailenjoyer.com/case/azure-asterism/ · Last updated

Markdown version

Cite a single fact by its ID, for example DD-166-F01 → https://detailenjoyer.com/case/azure-asterism/#DD-166-F01