Sapphire
The name “sapphire” can also apply to any corundum that’s not ruby, another corundum variety.
OVERVIEW
ABOUT SAPPHIRE
Besides blue sapphire and ruby, the corundum family also includes so-called “fancy sapphires.” They come in violet, green, yellow, orange, pink, purple, and intermediate hues. Some stones exhibit the phenomenon known as color change, most often going from blue in daylight or fluorescent lighting to purple under incandescent light. Sapphires can even be gray, black, or brown.
BIRTHSTONES & ANNIVERSARIES
Sapphire is the birthstone for September and the gem of the 5th and 45th anniversaries.
KASHMIR
Intensely saturated and velvety, rare sapphires from Kashmir set the standard for blue.
ROYAL BLUE
The world’s most famous engagement ring: Kate Middleton’s and Princess Diana’s sapphire.
PADPARADSCHA
A rare and valuable pinkish-orange sapphire named from the Sinhalese for lotus blossom.
FACTS
Mineral: Corundum
Chemistry: Al2O3
Color: Every color but red
Refractive index: 1.762 to 1.770
Birefringence: 0.008 to 0.010
Specific gravity: 4.00
Mohs Hardness: 9
TREATMENTS
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
SYNTHETICS
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
IMITATIONS
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
WHY WE LOVE THIS GEMSTONE
1
VIVID AND SATURATED
Sapphire’s blue can be vivid and saturated, like it’s lit from within.
2
DURABLE
It’s so durable, synthetic sapphire is used for the windows of supermarket scanners and spacecraft.
3
DELICATE SILK
Sapphire often contains delicate intersecting needles of rutile that gemologists call silk.
QUALITY FACTORS
Each color of sapphire has its own quality variations.
COLOR
CLARITY
CUT
CARAT WEIGHT
SAPPHIRE QUALITY FACTORS: THE COMPREHENSIVE GUIDE
RESEARCH
Explore sources, gemological research, and the role of gems in history
Nathan D. Renfro, Aaron C. Palke, and Richard B. Berg , Aug 6, 2018
John L. Emmett, Jennifer Stone-Sundberg, Yunbin Guan, and Ziyin Sun , May 7, 2017
Tao Hsu, Andrew Lucas, Robert E. Kane, Shane McClure, and Nathan Renfro , Aug 7, 2017
WHY WE LOVE THIS GEMSTONE
1
BEAUTIFUL CRYSTALS
Aquamarine grows in beautiful six-sided prismatic crystals that on rare occasions can be more than a foot long.
2
TRANSPARENCY
Faceted aquamarine is often exceptionally transparent with vitreous luster,
so it really sparkles.
3
DICHROIC
Using a dichroscope, you can see aquamarine is near colorless and stronger blue in different crystal directions.
Quality Factors
Assessment of the following characteristics determines aquamarine’s value.
COLOR
CLARITY
CUT
CARET WEIGHT
Aquamarine Quality Factors: The Comprehensive Guide
Research
Explore sources, gemological research, and the role of aquamarine in history.
Nicole Ahline and Maryam Mastery Salimi , Aug 7, 2017
