Nature’s gemstones

The column is not meant to be insensitive to robberies, murders, holdups, wars and disasters. I wrote it as a holiday diversion and to learn more about gemstones. Even I will admit here that the lecture I went through educated me on these wonders of nature – God’s creation.

At an afternoon lecture, Janina Dizon, a gemology student in Bangkok, Thailand, furthered our knowledge in gems. Janina Dizon’s mom is Jul Dizon, who owns the jewelry store at Shangri-La Hotel.

Home for just a week, she taught us that diamonds are formed in the earth’s mantle about 120-200 kilometers under the earth. The first "delivery" of diamonds would approximately be 2.5 billion years ago so it’s safe to say that the diamonds you see took about a million years to make! Diamonds are the only mineral species with one single element, which is carbon. Diamonds come in a range of colors – from the most common yellow to the rarest red. Diamonds are actually not rare; what is rare are good quality diamonds! Did you know that only 25 percent of diamonds end up as jewelry? Most are mined for industrial purposes – for windows in spacecraft, lasers and as tips for cutting metals.

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How should we buy diamonds? The four C’s are the most important factors to consider: Carat, which is the weight of the diamond. Color, wherein diamonds are assigned letter grades starting at D (which has virtually no trace of color) with successive letters corresponding to increasing traces of color, on through Z (light yellow). The fancy color designation is applied to stones with unusual colors like pink, blue, yellow, green to red. Clarity is the purity of the stone. The less internal characteristics the gem has, the rarer it is and consequently more expensive. The fourth is the cut, which affects the diamond’s brilliance and dispersion.

Incidentally, the largest diamond is the Royal Golden Jubilee. It was given as a gift to King Bhumibol of Thailand on his golden jubilee as reigning monarch.

The major sources are South Africa, Australia and Russia

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What interested me more was the colored gemstones. Any gem that is not a diamond is called a colored stone. Colored stones are divided into two mineral groups: Organic such as pearl, amber and shell; and non-organic such as jade, sapphire and emerald. Remember that all gems are precious regardless of price. Therefore the term semi-precious should be avoided because their beauty, rarity and durability characterize them as gemstones. They’re also a part of nature – God’s gift to us.

The value factors of colored stones are also color, clarity, carat and cut. Vivid, strong colors are usually the most valuable. For opaque stones like lapis lazuli, clarity usually has no meaning. Carat, the weight of the stone, is rarely problematic. Just weigh it on a jeweler’s scale. Often, higher carat weight simply means a higher price. Cut is the way the stone is fashioned, whether round, square, oval or pear-shaped.

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The most popular and more valuable gemstones on the market are: Corandum, which is the family name of sapphires and rubies. Sapphires come in a variety of colors but only the red color is categorized as a different variety, which is ruby. Identifying characteristics are fingerprint inclusions, needle-like inclusions called silk that intersect one another at 60-degree angle, color zoning and hexagonal growth lines.

The finer-quality rubies don’t ordinarily exceed three carats. Most commonly known as pigeon blood or bright red, the ruby is the most valuable.Cornflower-blue is the best color for sapphires. The major sources of sapphires are Myanmar, Thailand and Australia. Sri Lanka produces the lighter-colored sapphires.

From the beryl family comes a variety of aquamarines, which may range from greenish-blue to blue-green, although they are generally light in color tone. Green emeralds – from light to very dark green to very strong bluish green and morganite pink to light purplish red – are all beryl "relatives" found in Columbia, Brazil and Zambia.

And then there’s the pearl. The Philippines was in fact called the Pearl of the Orient Seas by the Spanish Empire because it was their only property in the Far East. Natural pearls are found in Sulu and Tawi-Tawi. Natives in the 14th century until today dive hundreds of feet under the sea without oxygen and return red-eyed from the saltwater. It is a tragedy that natural pearls are hardly found today in the Philippines.

Pearls are organic gems grown in freshwater and saltwater mollusks. About 99.9 percent of gem-quality pearls are cultured.

Pearls come in a variety of choices. There’s the South Sea pearls formed in saltwater, usually 10 millimeters or even larger. Freshwater pearls formed in freshwater come in an array of colors and are usually two mm. up to 10 mm. big. China and Japan produce a lot of freshwater pearls. The mabe pearl is a blister pearl "cemented" to the backing of a mother of pearl shell. Inside the mabe is a round bead, which is a kind of filler material.

Pearls can be bleached and dyed to alter the body color and hide blemishes. Irradiation produces black pearls or gray or blue-gray. You can check if pearls are dyed by looking around the drilled small hole. Detection is also possible through magnification and infrared photography.

To preserve your pearls, keep them away from heat and chemicals such as perfume and face creams. Avoid washing them in rough water. Rub them briskly but gently in your palms to make them glow. Pearls like body contact.

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Tourmaline is a gemstone that has a varied range of colors. It is the only gemstone that can generate an electrical charge when heated (pyroelectricity) or becomes electrically charged when pressure is applied to it (piezoelectricity). The most expensive colors are bright bluish-green to greenish-blue, also called the paraiba tourmaline. Other varieties include watermelon tourmaline, which is pink in the center and green around the edges. Another kind of tourmaline is the parti-colored, which has more than one color in it. Most tourmalines are heat-treated to either deepen or lighten their color. This enhancement is undetectable and commonly done. Major sources of tourmaline are Brazil and Afghanistan.

Topaz comes in a variety of colors, which include smoky topaz, brownish-yellow to orange and yellow-brown, to the most valuable imperial topaz which is reddish orange. Topaz is prevalent on the market and is often confused with citrine and brown quartz.

Almost all topazes are heat-treated to achieve the desired color. They can even simulate the colors of tourmalines, citrine and beryl and its major sources are Nigeria and Brazil.

The jade, the favorite of the Chinese, has two species: the jadeite jade and nephrite jade. The jadeite is one of the most valuable gemstones in the world. Jadeite is valuable because of its rarity, durability and a high demand for it. Jade is worn for good luck and its wearers were once considered to be only people of high rank and authority. Nephrite jade is known for its carvings.

The best quality jadeite is of an even and intense emerald-green color. It is known as the imperial jade and is also semi-transparent.

The only source for jadeite jade is Myanmar. Nephrite jade can be found in Taiwan, Canada, Australia and New Zealand.

The quartz has the distinct honor of having the most abundant varieties and gemstones in the world: from the rock crystal quartz which is colorless, to smoky quartz which is brown and rose pink. The aventurine, a member of the quartz family, sheds glittery reflections coming from within. The more popular varieties are the violet amethyst and the yellowish-orange citrine.

Enhancement for the quartz is through heating, which lightens the color of every dark amethyst. Brazil, Uruguay and Namibia are sources of quarts stones.

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Garnets range in a number of groups such as almandite which are typically dark red to rhodolite light to dark purplish red, yellow, green, brown and black to the yellowish orange and reddish orange, to name a few. Whew! So many colors. Most garnets are on the red side, so ironically the most expensive garnets are green, specifically the demantoid and tsavorite garnets. Major sources are from Sri Lanka and Brazil.

The chrysoberyl has only two groups in its family. One is the ever intriguing alexandrite and the chrysoberyl, which is yellowish-green to grayish-green. Alexandrite’s mystery lies in its color change phenomenon, which is scintillating. Its color changes from red by incandescent light to bluish green in fluorescent. There is no known enhancement for the alexandrite. Russia, Brazil and Sri Lanka are where alexandrite may be found.

So there you have it!

Thank you to Janine Dizon, her sister Candy and her brother Kuyang Cid.