Stinson's Gemcutting

Good Things to Know about Gems!

Some things to consider when you are buying jewelry 1. If you are going on a cruise and considering buying gems on board or on shore. Beware! Unfortunately there are a lot of overpriced goods people buy when they are on vacation. When you get home and decide to insure it, you may find out it appraises for much less than you paid! Most likely you will have trouble getting any kind of help from the cruise line, much less the seller.
2.Thinking about buying red topaz? It's most likely coated and not a permanent treatment.
3. Are you going to insure your gems? Check with your insurance company to see if they will let you replace a lost or stolen item from the same jeweler you bought from (and trust) and want them to do the replacement work. Some insurance companies won't pay unless you replace from some jeweler THEY choose. Hopefully it works out but what if the stones or craftsmanship don't suit you?
4. Are you considering buying natural red beryl? Watch for "filled" stones. Some dealers are changing the clarity of a faceted stone by infusing it with oil, epoxy or some other resin, and simply saying the stone has been "pressure treated". This treatment usually does improve the clarity however it also increases the price! Most importantly, this kind of treatment is also not considered permanent and can boil out when heated or ultrasonically cleaned and may also damage the stone. Any treatment that is not customary for the species should be disclosed by the seller!
5. Emeralds are one of the gems that are treated in so many ways it's hard to keep up with it all. They are oiled, infused with resins, glass and all manor of fillers. I recently heard of another treatment that was new to me. Some kind of resin is being used on stones that are so busted up, this stuff actually is glueing them together! Aparently it is not permanent as some stones are now turning color. One recent stone had been purchased for over $30,000 and now no one will touch it for repair. I got so sick of overpriced, busted up, motley colored, included junk emerald, that I decided to cut lab grown crystals. They are superior in every way and a fraction of the price. Read the next article below.

Laboratory Grown crystal vs Mined or Natural crystal

There always seems to be some strong opinions about the idea of owning a lab grown gem. First and foremost, whatever it is, lab, all natural or treated natural should always be made known to the buyer. Before going too far, make sure you know the difference between a lab grown gem and a simulated gem. A simulant or simulated gem is a stone that simulates or imitates another species. Cubic zirconia is used to simulate a diamond for example. However a lab grown sapphire IS a real sapphire. It doesn't simulate or imitate it, it is exactly the same as sapphire that comes out of the ground, only cleaner, larger, more consistent color and very much cheaper. I have cut most popular species and many rare stones since I started cutting in the 1970's. There have been several things that have been the basis of my decision to cut lab grown crystal, and that is, 1. what my customer wanted 2. the customer's budget and 3. the availability of suitable rough. High prices and scarce rough have driven man to search for cheaper, larger and cleaner crystals by trying to grow them in a lab, for over a hundred years now. It's nothing new. If you have plenty of cash and can afford the finest and that's your desire then you are fortunate. I just hate to see someone deny themselves of owning a stunning gem in a nice size and beautiful color ONLY because the rough crystal was grown in a lab. Read the following analogy and decide for yourself and don't let someone else dictate your tastes (or budget) to you!
I was told the following analogy recently and I think it is excellent. Here's one way to think about the difference. Two identical rose seeds are planted. One is planted in a natural outdoor garden by a gardener. The other is planted by a greenhouse nurseryman. Each is cared for with the proper water and food. Each produces a nice green rose bush and they soon flower. The "natural" flower has a nice fragrence and size but some of it's petals are torn or bruised. Some of it's leaves have been chewed by insects and overall appearance is not the best due to recent wind and a heat wave. The greenhouse rose is also fragrent and large. It's flower is complete and beautiful and having no wind, heat, or insects to fight, it's leaves and overall appearance are picture perfect.
Natural crystals and lab grown crystals can be similarly compared. They are the same chemical composition and have the same characteristics. Natural crystals usually have some trace elements, impurities etc. that a lab crystal may not have. These may cause inclusions to cloud or muddle the color. The natural crystals are at the mercy of Mother Nature and all of her forces, so it is natural to expect many variations in color, size and clarity. Because it takes special conditions to produce a given species, there may be plenty of crystals or they may be very hard to find. The lab crystal growth is conducted under proper heat, pressure and time with no outside influences. Lab crystals are extremely clean, large and their color is consistent. Very important is the fact that crystals can be grown and usually priced much cheaper than the more expensive natural crystals. There is one important thing that should be mentioned when buying ANY stones. That is that the fact that the stone has been lab grown or is natural. Also if a natural stone then the seller should disclose any treatments that have been made to the stone. Any treatments should be fully disclosed by the seller!

What stones make good jewelry?

There's more to a gem than what's graded in the 4 "C's" (color, cut, clarity and carat weight). Many other factors should weigh in your decision to buy a stone. These are physical characteristics that make a good gem what it is: First, wearability or hardness. A stone should hold up to normal wear and not scratch easily. Our hands take such an everyday abuse, knocking around, grabbing, holding, scraping against everything from brick to steel, it's asking alot for a stone to keep it's sparkle when it's mounted in a ring especially. Pendants usually don't go through such a daily beating, but some people still take off a nice pin or necklace and just toss it in a jewelry box or on a dresser to bang against other pieces, pocket change, keys or whatever else is there. So much depends on the wearer. I've sold rings that are back for repair in a six months, with the prongs beat up and stones chipped because the wearer didn't respect the beauty and character of the stone. Even with a good mounting that is heavy and protective, any stone can be damaged. Diamonds can be chipped. Even though diamond is the hardest stone, it is also brittle!
That brings up the second thing that makes a good stone, toughness. Toughness is a physical character that many stones exhibit even though they are not nearly as tough as a diamond. Brittleness and toughness and two different things entirely. A good example is aquamarine and peridot. Both are birthstones and two different species and different hardnesses. Aqua is quite tough and can be mounted and worn much easier than peridot which is more brittle. I could hammer a piece of jade with a considerable blow. The same force could be stong enough to break a diamond, because jade has a tougher character.
Heat sensitivity is another character that some stones exhibit -- opal is the worst problem child in this category. Any opal lover will tell you not to expose a fine opal ring to freezing cold and then immediately warm hands by a roaring fireplace! Many stones have some level of heat sensitivity, and while this is something that I must consider when cutting, normal everyday temperature variations are not very important with most species.
So, what stones make good jewelry? First, diamond is still king in hardness and it's generally tough enough that few are aware that it is somewhat brittle too. But why not enjoy some color in your life? The top stone after diamond has to be sapphire. Sapphire comes in ALL colors, not just blue! (Ruby is also included here, as ruby is just a red sapphire!) Sapphire is the next best thing in hardness, it's tough and has no heat sensitivity, cleavage or light problems. My absolute first choice in colored stones.
Second on my list is spinel. It's available in nearly all colors, it's hardness at 8 places it just below sapphire. It's tough, not heat sensitive, presents no problems and is VERY under rated.
My third pick is topaz. It's next in hardness at 8 but does present a problem with a perfect cleavage just like diamond. It is limited in color, but overall makes a very wearable stone.
Fourth is one of my favorite species: beryl. Gem beryl varieties are emerald (green), aquamarine(blue), heilodor(yellow), morganite(red), goshenite(clear) and bixbite(red) Beryl is 7 1/2 to 8 in hardness, it tough and not brittle or heat sensitive. The variations in color between the various available colors give a wide range to choose from.
The tourmaline group is another good choice because of the available colors, and hardness only slightly below beryl. However it is brittle and more heat sensitive.
Finally the quartz species rounds out the well know stones. Crystalline Varieties: amethyst, citrine, ametrine, rose, smokey, rutilated and the cryptocrystaline varities: chalcedony, carnelian, sard, chrysoprase, agate, onyx, & jasper. Quartz has respectable hardness at 7; crystaline varieties are often brittle while cryptocrystaline forms are sometimes exceedingly tough.
This covers a good bit of the popular stones available, but is only the tip of the iceberg as there are many many more species not mentioned.

What is the difference between carat, karat and carrot?

Carat is a measure the weight of gems. One carat is defined as 200 milligrams or 1/5 of a gram. Or another way of saying it is there are 5 carats in one gram. A carat is further divided into points. 100 points = 1 carat. So a stone that is said to be 50 points will weigh 1/2 ct. (.5 ct) or 100 mg. A stone that is 1/4 ct would be 25 points (.25 ct) or 50 mg.
Karat is a measure of the purity of gold. Gold is mixed or alloyed with other metals, such as copper, zinc, silver etc. to give it better wearing qualities and sometimes different color. Pure gold is 24 karat and is too soft to securely support and protect a fine gem. So to strengthen it gold is mixed with copper. When it is called 14 kt. it is 14/24 pure gold or 58.3% pure. 18 kt. gold is 18/24 pure or 75% pure.
Carrot is a measure of rabbit especially Bugs Bunny!

How do you clean a ring/stone?

Plain gold rings can be buffed up with a small amount of red rouge (try lipstick!) on a soft cloth. For heavy scratches, it's best to stop by your favorite jeweler and ask if they will buff the ring for you. Most are happy to get you in the store and will not charge for this, but be sure to ask if you are not sure. They will also clean your stones at the same time or you can clean them yourself at home. For common faceted stones diamond, sapphire etc., use warm water and a grease cutting detergent such as Dawn. Use a small toothbrush and scrub the stone wherever you can reach it through the prongs. Increase the temperature of the water gradually until it is hot. In cleaning a stone, the trick is not to shock a stone by suddenly immersing it in extremely hot water. (Don't do this with opals!) Soaking in a detergent and ammonia solution may also help to loosten oil buildup on the stone. If you are serious about your jewelry, buy a small ultrasonic cleaner and use a solution of ammonia and a few drops of dawn in the water tank. A WORD OF CAUTION: I recommend NOT cleaning emeralds with an ultrasonic. Mined emeralds are usually treated and lower quality included/flawed stones may be damaged or actually fall apart in an ultrasonic! If you have a filled diamond it is also not recommended to clean with an ultrasonic! Most faceted stones should not be any problem however. Cabochons may generally be cleaned the same way. Start with warm water and gradually increase the temperature. Use a brush and some good detergent. Stones that are heat sensitive (opal), soft (amber) or porous (turquoise) should not be cleaned like this. When in doubt, it's best to go to the source if possible. The manufacturer, the one who cut the stone probably knows more about it than the salesman. If you can't find the cutter, I recommend the next person to ask is a GIA Gemologist. (Find one with the G.G.title if you can.) If you strike out on the first two, then be sure to ask your favorite independent jeweler. Last on the list would be chain and mall stores, because they often staff the sales counter with part timers and newbies with little experience and no practical educational background.

Should my ring be stamped?

There are both federal and state laws concerning the stamping of jewelry quality. The National Stamping Act defines how a jewelry item is to be stamped for identification. However state laws may vary on the subject of qualtiy and standards of fineness. The thing to remember is that articles are NOT required to carry a quality (karatage) stamp. When a manufacturer does not use a trademark identification, then the item of jewelry should NOT carry a quality stamp.

How is a stone graded for clarity?

These comments are based on the Gemological Institute of America clarity grading system. (GIA is generally considered the world authority on standards in the gem industry.) First of all it must be understood that gems grow under a wide variety of conditions in nature. Generally, clarity in the GIA system, is graded using the following guidelines to establish a clarity grade numbered 1 to 10. Some stones usually grow under conditions that produce very clean or flawless crystals.These are classed as TYPE One. Some species commonly have small amounts of other minerals that grow inside them when they are formed (called inclusions) which are expected and do not downgrade the gem. These are TYPE TWO. Finally there are gems that usually found with many inclusions or flaws. More tolerance is allowed when grading these gems and inclusions should not downgrade value. These are TYPE THREE stones. Examples: Type I: aquamarine, topaz; Type II: sapphire, garnet; TYPE III: emerald, Paraiba tourmaline, red beryl (bixbite).
GIA's numbers overlap and I personally don't like having a number in two grades, so here is my clarity grades:
1-3 COMMERCIAL GRADE: Type 1 is heavily included under 10X. Type II has visible inclusions to the eye. Type III stones will be noticeably to excessively included to the eye.
4-6 GOOD: Type I stones will be slightly included under a 10 power loupe. Type II stones more included and may be visible to the eye. Type III are slightly visible to the eye with no magnification.
7-8 FINE: Type I stones are very slightly included under 10X. Type II stones are slightly included under 10X. Type III stones are only very slightly included to the eye.
9-10 EXTRA FINE: Type I stones are flawless or nearly flawless under a 10 power loupe. Type II stones are very slightly included under 10X and Type III stones are clean to the eye but will be slightly included under 10X.

This is how I classify the general clarity of gems:
FACET GRADE the above GIA system is used to describe "facet grade" quality stones.
CABOCHON GRADE means stones that are usually not suitable for faceting but that can be cut as a cabochon i.e., rounded off in a geometrical shape. There are facet grade cabs available in some species. Also some cryptocrystaline varieties-- agates, jaspers for example-- are usually cut as cabochons, but sometimes these are also faceted. An example would be black onyx.
TUMBLE GRADE means stones that are good for polishing with a tumbler. These are generally smaller pieces or pieces that are so fractured that they are not suitable for cutting cabochons.
SPHERE GRADE means stones that are solid and generally are very clean and with only minor flaws.
WATCH GRADE means stones that are solid and extremely clean to flawless, these are thin slices used for faces of wrist watches.
CARVING GRADEdefines stone that is large and clean enough to carve or sculpt. It is solid with very few flaws.
On the lighter side, if someone says they have a "rabbit rock", it means a stone only suitable for throwing at a rabbit. If you are are out prospecting and your partner says the stone you've just showed him is a "leaverite", it means it's worthless and to "leave 'er right" where you found it.

Questions or comments? We're always glad to hear what you have to say and appreciate any good tips or information you have to share. Simply email me. stinsons@gemservice.com

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This page was updated December 12, 2007