Yellow has long held a place of significance in the world of gemstones, representing everything from divine goodness and faith to secrets and generosity. While some gems are renowned specifically for their yellow hues, many others exhibit this vibrant color as part of a broader spectrum. This article explores the diverse range of gemstones considered yellow birthstones, delving into their history, geological origins, gemological properties, and cultural significance, as understood through historical and gemological sources.
History and Lore
The association of yellow with gemstones dates back to ancient times. Color held a high significance, with yellow worn by those keeping secrets and, conversely, as a symbol of generosity by women. Christian symbolism further imbued yellow with meaning, representing God’s goodness and faith. Alchemists of the old times prescribed yellow crystals to treat ailments like liver issues and jaundice.
Historically, topaz was considered the true yellow gemstone, a belief rooted in ancient interpretations of the biblical high priest’s breastplate, which was set with twelve gems. The second crystal, called pitdah in Hebrew, is widely believed to have been topaz, and in antiquity, a true topaz had to be yellow. The Roman empire also embraced yellow gemstones, with Emperor Nero popularizing amber after referencing his wife’s “amber-colored” hair, sparking a fashion trend.
Geological Formation and Sources
The origins of yellow gemstones are as varied as the stones themselves. Topaz, a silicate mineral of aluminum and fluorine, is typically found in pegmatites near silica rock of volcanic origin. Significant sources of topaz are located in Europe, particularly Germany. Citrine, a variety of quartz, forms in volcanic rocks. Sapphires, while most commonly known in blue, occur as yellow gemstones from the mineral corundum, second only to diamond in hardness.
Other yellow gems have unique geological origins. Yellow opal forms in various types, including wax opals from Europe, fire opals from Mexico, lemon opals from the US, and common opals from Australia. Rhodizite and londonite, borate minerals, are found as yellow stones, resisting weathering due to their mineral composition. Yellow tourmaline originates from the species dravite and elbaite, mined in Brazil and Africa. Garnets, typically red, also occur in yellow varieties from spessartine, andradite, and grossular species. Zircon, another yellow gemstone, is found in various geological settings.
Gemological Properties
The gemological properties of yellow birthstones vary considerably. Yellow topaz, a popular choice for jewelry, registers an 8 on the Mohs hardness scale, making it suitable for daily wear. Citrine, also a quartz crystal, has a hardness of 7, offering good durability. Sapphires, including yellow varieties, boast a hardness second only to diamond.
Other yellow gems exhibit different properties. Yellow spinel, while often red, can be extremely rare in yellow hues and is primarily a collector’s item. Yellow sphene (titanite) is prized for its brilliance, exceeding even diamond, though its hardness is lower. Yellow tourmaline, though rare, comes from dravite and elbaite species. Cymophane, the yellow variety of chrysoberyl (cat’s eye), is the third hardest gemstone, after diamond and corundum, and is valued for its chatoyancy. Yellow garnet, occurring in spessartine, andradite, and grossular, is a traditional birthstone for January.
Here's a table summarizing the hardness of some of the discussed yellow gemstones:
| Gemstone | Mohs Hardness |
|---|---|
| Yellow Topaz | 8 |
| Citrine | 7 |
| Yellow Sapphire | 9 |
| Yellow Garnet | 6.5 - 7.5 |
| Cymophane | 8.5 |
| Yellow Sphene | 5.5 - 6 |
A Diverse Range of Yellow Gems
Beyond the more commonly recognized yellow birthstones, a multitude of other gems can exhibit this color. Agate, chalcedony, beryl, rock crystal, jasper, spinel, and zircon can all occur in yellow shades. Cat’s eye is also accepted as a yellow birthstone. Amber, though technically a resin and not a gemstone, has historically been considered a yellow birthstone. Jade, typically green, can also be found in yellow varieties. Sunstone, idocrase (vesuvianite), and peridot (which can range from green to yellow-green) also contribute to the spectrum of yellow gemstones. Yellow rhodizite and londonite, borate minerals, are rare and valuable. Yellow opal, encompassing various types like wax, fire, lemon, and common opal, is a traditional and modern birthstone for October.
Symbolism and Metaphysical Beliefs
Throughout history, yellow gemstones have been imbued with symbolic meaning. Beyond the historical associations with secrets and generosity, citrine is known as the “Merchants Stone,” symbolizing hope and strength. Yellow crystals were historically believed to aid in treating liver issues and jaundice. The color yellow itself was considered emblematic of God’s goodness and faith.
Care and Cleaning
The care required for yellow gemstones varies depending on their hardness and composition. Topaz and citrine, with hardnesses of 8 and 7 respectively, are suitable for daily wear and can be cleaned with warm, soapy water and a soft brush. Sapphires, being very hard, are also durable and can be cleaned similarly. Softer stones like yellow sphene require more careful handling and should be cleaned gently to avoid scratches. Cymophane (cat’s eye) should be protected from harsh chemicals and ultrasonic cleaners. Garnets are relatively durable but can be chipped with a sharp blow. Regular cleaning with a soft cloth and mild soap will help maintain the brilliance of all yellow gemstones.
Conclusion
The world of yellow gemstones is remarkably diverse, encompassing a wide range of geological origins, gemological properties, and historical significance. From the ancient reverence for yellow topaz to the modern appeal of citrine, these stones have captivated humanity for centuries. Whether valued for their beauty, durability, or symbolic meaning, yellow gemstones continue to hold a special place in the hearts of gem enthusiasts, jewelry buyers, and those seeking a connection to the earth’s natural wonders. The spectrum of yellow gems offers a vibrant and enduring legacy, representing a rich tapestry of history, science, and cultural lore.