August’s Birthstones: Peridot & Spinel

PeridotCropped

Peridot

The fresh lime green of peridot is its distinctive signature, and the gem is one of few that occur in only one color, a rich yellow-green. Peridot’s apple-green hue has been treasured for over 4,000 years. The Ancient Egyptians revered it as the “gem of the sun”. The location of Egypt’s fog-shrouded volcanic mines on the Red Sea island of Zabargad were a closely guarded secret, and stones they dug from there are the source for many large fine peridots currently in the world’s museums. The Romans dubbed it “evening’s emerald” because unlike the deep-green emerald, Peridot’s citrus tones remain constant even by candlelight. In the Middle Ages, Europeans adorned cathedrals with fine peridot stones.

Peridot-USGS

Uncut peridot from the San Carlos Reservation.

Although Hawaii’s volcanoes have produced some peridot large enough to be cut into gemstones, virtually all peridot sold in Hawaii today is from Arizona, another state with extreme geology. Most of it is mined, often by hand, by Native Americans on the San Carlos Apache (Nde) Reservation in Arizona. Peridot found here is beautiful in color but relatively small in size. Faceted peridot from Arizona is rare in sizes above five carats.

page24-1036-full

A large peridot in a pendant by Paula Crevoshay.

In 1994, an exciting new deposit of fine peridot was discovered in Pakistan, 15,000 feet above sea level in the far west of the Himalaya Mountains in the Pakistanianpart of Kashmir. The gemstone can be found in North America in Arizona, Arkansas, Hawaii, Nevada, New Mexico and Mexico. Other sources include areas in Australia, Brazil, China, Egypt, Kenya, Myanmar (Burma), Norway, Kashmir, Saudi Arabia, South Africa, Sri Lanka, and Tanzania.

Peridot is also one of the few gemstones to be found to come from outer space. Found in pallasite meteorites, extraterrestrial peridot is one of the rarest gem materials on Earth. In 2005, peridot was found in comet dust brought back from the Stardust robotic space probe.

Peridot is harder than metal but softer than many gemstones. Store peridot jewelry with care to avoid scratches and protect from blows. Because peridot is sensitive to rapid changes in temperature, never have it steam cleaned and avoid ultrasonics. Clean with mild dish soap: use a toothbrush to scrub behind the stone where dust can collect.

R79-Red-Spinel

Red spinel in an Alex Sepkus ring, available at Studio Jewelers.

Spinel

Spinel’s name comes from Latin “spina”, meaning “arrow”. You may also find spinel in black, violet blue, greenish blue, grayish, pale pink, mauve, yellow or brown. Vivid red is the most desirable color of spinel gemstones, followed by cobalt blue, bright pink and bright orange. The more affordable stones are often those with paler colors, like lavender.There is a unique natural white spinel, now lost, that surfaced briefly in what is now Sri Lanka. With a hardness of 8 on the Moh’s scale, spinel is a durable gemstone suited for any type of jewelry.

page5-1000-full

Blue and red spinel with diamonds in a unique ring by Julie Rauschenberger.

In ancient Sanskrit writings, the gemstone spinel was called the “daughter of ruby”, and for centuries, red spinels were called spinel-rubies or balas rubies.  “Balas” is derived from Balascia, the ancient name for Badakhshan, a region in central Asia. Mines in the Gorno Badakhshan region of Tajikistan were the main source for red and pink spinels for centuries.

R19-Pink-Spinel-front

Pink spinel and diamonds in a ring by Alex Sepkus, available at Studio Jewelers.

It wasn’t until 1783 that spinels were differentiated from rubies. The two gemstones can be distinguished on the basis of their chemical properties: a red spinel is a compound of magnesia, iron, oxygen, and chromium, while a ruby is a type of aluminium oxide. After the 18th century the word ruby was only used for the red gem variety of the mineral corundum and the word spinel came to be used.

Imperial_State_Crown

The Black Prince’s Ruby, actually a red spinel, in the front of the Imperial State Crown on England.

Examples of famous rubies that are actually spinel include pieces in the British Crown Jewels. One is called the “Black Prince’s Ruby,” which is actually a 170-carat red spinel. Similarly, The Timur Ruby, a 352-carat gemstone once owned by Mogul emperors and now held by Queen Elizabeth, was also recently discovered to be a red spinel. Part of the reason behind the misidentification of these gemstones is that spinel is often found in the same gemstone bearing gravels as ruby and sapphire. Distinguishing features, like its octahedral crystal structure and single refraction, are what sets it apart from other gems. Spinel also has a lower Mohs hardness than ruby and sapphire.
Spinel has long been found in the gemstone-bearing gravel of Sri Lanka and in limestones of the Badakshan Province in modern-day Afghanistan and Tajikistan; and of Mogok in Burma. Recently gem quality spinels also found in the marbles of Luc Yen (Vietnam), Mahenge and Matombo (Tanzania), Tsavo (Kenya) and in the gravels of Tunduru (Tanzania) and Ilakaka (Madagascar).

Article sources include:

https://agta.org/education/gemstones/peridot/

https://www.gia.edu/peridot

https://www.americangemsociety.org/page/augustbirthstones

https://agta.org/education/gemstones/spinel/

https://www.americangemsociety.org/page/augustbirthstones

https://en.wikipedia.org/wiki/Spinel

https://kimberlycollinsgems.com/products/spinel/ 

Advertisements

Ruby – Birthstone of July

 

agtaRuby600

Ruby photo courtesy of the AGTA.

Noted in ancient Sanskrit writings and the Bible as the most precious of all gemstones, rubies have been the prized possession of emperors and kings throughout the ages. Ruby’s inner fire has been the inspiration for innumerable legends and myths, and to this day, no red gemstone can compare to its fiery, rich hues. It was believed wearing a fine red ruby bestowed good fortune on its owner.

DMI4-Ruby-and-Diamond

Hand-pierced and engraved ruby and diamond ring by Dmitriy Pavlov, available at Studio Jewelers – Madison, WI.

 

Many people associate its brilliant crimson colors with passion and love, making ruby an ideal choice for an engagement ring. Ruby is the red variety of the corundum mineral species, while all other colors of corundum are called sapphire. In the United States, a minimum color saturation must be met to be called a ruby; otherwise, the stone will be called a pink sapphire.

AS-Ruby-R166

Alex Sepkus ring with 1.07 ct. ruby and diamonds, available at Studio Jewelers – Madison, WI.

 

Rubies have a hardness of 9.0 on the Mohs scale of mineral hardness. Among the natural gems only moissanite and diamond are harder, with diamond having a Mohs hardness of 10.0 and moissanite falling somewhere in between corundum (ruby) and diamond in hardness. This makes ruby an excellent choice for a ring or other piece of jewelry to be worn everyday.

CK-ruby-custom

Custom made ruby and diamond ring by Chris Keenan.

This most sought after gemstone is available in a range of red hues, from purplish and bluish red to orangish red. Ruby is readily available in sizes up to 2 carats, but larger sizes can be obtained. However, in its finest quality, any size ruby can be scare. In readily available small sizes, ruby makes an excellent accent gemstone because of its intense, pure red color

512px-Corundum-winza-17d

Ruby crystal, photo by Rob Lavinsky, iRocks.com via Wikipedia.

Ruby is mined throughout Southeast Asia, and historically, the Mogok Valley in Upper Myanmar (Burma) was for centuries the world’s main source for rubies. The Republic of Macedonia is the only country in mainland Europe to have naturally occurring rubies. A few rubies have been found in the U.S. states of Montana, North Carolina, South Carolina and Wyoming. The gemstone spinel is often found in the same gem gravel areas as ruby, and many famous historic gemstones thought to be rubies have been found to actually be spinel.

Despite all the best efforts of gemstone merchants to use technology to enrich color, fine ruby is still exceptionally rare. After being extracted from the earth, rubies today are commonly heated to high temperatures to maximize the purity and intensity of their red hue. Impurities may also dissolve or become less noticeable after heating. However, heating will only improve the color if the gemstone already contains the chemistry required. 

———-

In addition to the above information from the AGTA, Wikipedia and other sources, you can find facts about these of gems and more at the Gems and Gem Materials online course, through the University of California-Berkeley’s Department of Earth and Planetary Science. The website is available for the general public, and contains a wealth of information for the budding gemologist and anyone interested in learning more about gemstones. Hanna Cook-Wallace has contributed to this site, which was developed by Jill Banfield while teaching at the University of Wisconsin.

Birthstones of February

Amethyst

agtaAmethyst-600

Faceted Amethyst gemstones from the AGTA. 

Happy birthday, February babies! Your birthstone is Amethyst, a violet variety of quartz.  Amethyst is a semiprecious stone and is the traditional birthstone for February. Amethyst owes its violet color to irradiation, iron impurities, and the presence of trace elements. Amethyst occurs in primary hues from a light pinkish violet to a deep purple. Amethyst may exhibit one or both secondary hues, red and blue. (Green quartz is sometimes incorrectly called green amethyst, which is a misnomer and not an appropriate name for the material, the proper terminology being prasiolite).

ame-crystal

Amethyst crystals from a cluster here in the store. 

The Greek word “amethystos” may be translated as “not drunken”, from Greek a-, “not” + methustos, “intoxicated”. Amethyst was considered to be a strong antidote against drunkenness, which is why wine goblets were often carved from it. In his poem “L’Amethyste, ou les Amours de Bacchus et d’Amethyste” (Amethyst or the loves of Bacchus and Amethyste), the French poet Remy Belleau (1528–1577) invented a myth in which Bacchus, the god of intoxication, of wine, and grapes was pursuing a maiden named Amethyste, who refused his affections. Amethyste prayed to the gods to remain chaste, a prayer which the chaste goddess Diana answered, transforming her into a white stone. Humbled by Amethyste’s desire to remain chaste, Bacchus poured wine over the stone as an offering, dyeing the crystals purple.

ame-beads

Close-up shot of some faceted Amethyst beads available here at Studio Jewelers.

It was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglio engraved gems. Beads of amethyst were found in Anglo-Saxon graves in England, and Medieval European soldiers wore amethyst amulets as protection in battle in the belief that amethysts heal people and keep them cool-headed.  Some Tibetans consider amethyst sacred to the Buddha and make prayer beads from it. Purple has long been considered a royal color, so it is not surprising that amethyst has been so much in demand throughout history. Fine amethysts are featured in the British Crown Jewels and were also a favorite of Catherine the Great and Egyptian royalty. In the Old World, amethyst was considered one of the Cardinal gems, in that it was one of the five gemstones considered precious above all others. Great thinkers like Leonardo da Vinci believed that amethyst could dissipate evil thoughts and quicken the intelligence. Anglican bishops wear an episcopal ring often set with an amethyst, an allusion to the description of the Apostles as “not drunk” at Pentecost in the Bible.

ame-group-side

A small selection of Amethyst jewelry available here at Studio Jewelers.

There is an excellent article on the history of Amethyst online at the Thoughts on Jewelry blog at https://thoughtsonjewelry.wordpress.com/2012/08/18/history-of-amethyst/ . Thanks and credit to Wikipedia.com and AGTA for information used in this article. 

 

December’s Birthstones

Birthstones of December

Tanzanite, Zircon, and Turquoise

Photos and some information courtesy of AGTA. Thanks also to Wikipedia.com and Geology.com. You can also visit our Tanzanite, Zircon and Turquoise boards on Pinterest for more photos and info!

agtaTanzanite600

Tanzanite

Tanzanite was added to the birthstone list by the American Gem Trade Association in 2002, the first gemstone added since 1912. The gemstone is an exotic, vivid blue, kissed by purple hues. Tanzanite has the beauty, rarity and durability to rival any gemstone.

Tanzanite is mined only in Tanzania at the feet of the majestic Mount Kilimanjaro. Legend has it that the gem was first discovered when some brown gemstone crystals lying on the dry earth were caught in a fire set by lightning that swept through the grass-covered hills. The Masai herders driving cattle in the area noticed the beautiful blue color and picked the crystals up, becoming the first tanzanite collectors.

One of the most popular blue gemstones available today, tanzanite occurs in a variety of shapes and sizes and also provides a striking assortment of tonal qualities due to remarkably strong trichroism. Rarely pure blue, tanzanite almost always display its signature overtones of purple. Tanzanite can also appear differently when viewed under alternate lighting conditions. The blues appear more evident when subjected to fluorescent light and the violet hues can be seen readily when viewed under incandescent illumination. In smaller sizes, tanzanite tends toward the lighter tones and the lavender color is more common. While in larger sizes, tanzanite typically displays deeper, richer color.

agtaBlueZircon600

Zircon

Zircon is a popular gemstone that has been used for nearly 2000 years. It occurs in a wide range of colors and has a brightness and fire that rivals those of diamond. Zircon should not be confused with cubic zirconia, which is a man-made material. In the middle ages, zircon was said to aid sleep, bring prosperity, and promote honor and wisdom in its owner. The name probably comes from the Persian word zargun which means “gold-colored.” The fiery, brilliance of zircon can rival any gemstone. The affordability of its vibrant greens, sky blues, and pleasing earth tones contributes to it’s growing popularity today.

Zircon is mined in Cambodia, Sri Lanka, Vietnam, Thailand, and other countries. Because it can be colorless, green, blue, yellow, brown, orange, dark red, and all the colors in between, it is a popular gem for connoisseurs who collect different colors or zircon from different localities.

12decemberturquoise600

Turquoise

Turquoise is among the oldest known gemstones- it has been mined since 3,200 BC. Isolated from one another, the ancient people of Africa, Asia, South America and North America independently made turquoise one of their preferred materials for producing gemstones, inlay, and small sculptures. It graced the necks of Egyptian Pharaohs and adorned the ceremonial dress of early Native Americans. This robin egg blue hued gemstone has been attributed with healing powers, supposedly promoting the wearer’s status, wealth, well being, and luck.

Turquoise is an opaque, light to dark blue or blue-green gem, the finest color is an intense blue. Turquoise forms best in an arid climate, and that determines the geography of turquoise sources. Most of the world’s turquoise rough is currently produced in the southwestern United States, China, Chile, Egypt, Iran, and Mexico. In these areas, rainfall infiltrates downward through soil and rock, dissolving small amounts of copper. When this water is later evaporated, the copper combines with aluminum and phosphorus to deposit tiny amounts of turquoise on the walls of subsurface fractures.

Turquoise may contain narrow veins of other materials either isolated or as a network, these can be black, brown, or yellowish-brown in color. Known as the matrix, these veins of color are sometimes in the form of an intricate pattern, called a spider web. Some turquoise localities produce material with a characteristic color and appearance. People who know turquoise can often, but not always, correctly associate a stone with a specific mine.

Welcome!

Hello all, and welcome to our new blog! Hanna Cook-Wallace has been in the jewelry business for most of her life, and has worn many hats in the industry. We’ll be sharing her thoughts and knowledge here, as well as posts by Studio Jewelers staff members.

Please bear with us as we wade through some technical difficulties along the way, as this is a “journey of discovery” for Lisa, our webmaster. Off we go!