Monday, June 30, 2008 Specific Gravity Precision Checker

How accurate is specific gravity? Dev put together a quick reference chart and an SG Scale Precision Checker that allows you to see how accurate (and inaccurate!) the measurement of SG can be depending on the precision of your scale. The precision of the scale and the weight of the stone being weighed are critical to getting an accurate measurement of specific gravity.

Monday, June 16, 2008 International Schools of Gemology Comparison Chart

When I started researching where I wanted to take gemology classes, I had a hard time comparing all the different choices. So, I have put together this chart to help compare schools. Trying to find all the information on each school can require some digging, so this is a work in progress. If you can help fill in any of the blanks, please let me know.

I've finally decided on the distance classes at GIA (Gem-A was a close second!) I like that I can take the program one class at a time, and have been very happy with the class materials. I've finished the diamonds class and am in the middle of the colored stones class. I'll be taking the lab classes in August and can't wait!

If you are looking for great information with a much smaller price tag (as in free or close to it) try the International Gem Society or Dr Barbara Smigel's Online Class. Both are fantasitic resources for rockhounds!

Monday, June 09, 2008

Gemology Myths

All spectroscopes have wavelength scales.
Most gemological spectroscopes do not; the wavelength scale requires a 2nd tube.
You only have to do one test to identify a gemstone.
Most gemologists conduct at least 3 tests if not more.
All gemstones have an absorption spectra.
Most clear stones tend not to have an absorption spectra, or it is so fine as to be unreadable with handheld tools.
All you need is a refractometer to identify gemstones.
A refractometer is very helpful, since the refractive index (RI) is very unique for gemstones. But the caveats include:
Some stones are very close to each other by RI.
Some stones can range broadly as the impurities are different from locality to locality.
Some stones are off the scale, over RI 1.80 for most refractometers.
The refractometer cannot detect synthetics or treatment which you need to know.
Gemologists only use brand name gemological tools.
Some gemologist insist this is the only way to go. If your customers are image conscious, then it might be worth the extra thousand dollars. But if your customers appreciate value, then you can use tools that are just as accurate and save you money which is why is here!
All gemstones are natural.
While many gemstones are natural, synthetics have become more and more prevalent. Multiple tests have been devised to differentiate natural gemstones from synthetics.
Only natural gemstones are valuable.
Some synthetic gems are more valuable than natural gemstones! For example, a synthetic hydrothermal emerald gemstone is worth more than a clear quartz gemstone of the same size and quality.
Only untreated, natural gemstones are valuable.
Many treated natural gems are very valuable, and some synthetics are not cheap. Take Paraiba tourmaline for example, which can be heat treated and still worth $1000's per carat.
Bought it as [[pick a gem]]. It has to be [[pick a gem]]. Variations include:
My jeweler can't miss.
Has to be true, saw it on TV!
From my grandmother, so it must be alexandrite.
Family heirloom, must be ruby.
Look how old it is, doesn't age count for amethyst?

Unfortunately, we all make honest mistakes. And there are some who make a living at it. Most jewelers are honest so don't feel like you have to be paranoid. At the same time, always learn for yourself or get more than one opinion from people you can trust or who don't have a vested interest. The best example is to never, ever sell your gemstone or family heirloom to an appraiser who just told you what it was worth and then offered to buy it! Along the same lines, if you are a year or two into gemology, admit that you still have alot to learn! This will help you save face when you want to dig your heels in during a debate. Back away slowly, do your research, and come back for more when you know more.
All gems are suitable for jewelry
Many gems are much too soft for jewelry. Others are too soft for rings but should be safe enough for earrings unless you plan on banging your head against the wall!
Sapphire is only blue.
Sapphire comes in many colors from pink to purple, to clear, to yellow or padparadscha!
Diamonds are rare.
The truth is that cheap diamonds are rare. Geologically speaking, diamonds are as plentiful as tourmalines which puts them on the fairly common side of gemstones. For investments, choose natural untreated rubies or high quality emeralds.
Generic gemological equipment can not compare to brand name equipment. has used most gemological equipment available in the market. We are very pleased to see that our value-focused high quality instruments are very accurate and offer an excellent alternative to high priced brand-focused products that can cost thousands more to purchase.
All rubies are valuable.
Some rubies look like gravel and that is true for any gem material. But there are some natural rubies that have been extensively treated to fill in cracks and cover inclusions that make them far less valuable than merely heated treated rubies or the much more esteemed all natural rubies. Even all natural rubies must be over one carat then have very good clarity and color to be valuable.
I found it gem digging; I'm rich!
There is no measuring sentimental value. I still have my biggest and ugliest garnet found while gemdigging sitting like a precious trophy in my collection. Most gemdigging finds are worth more as the memories they bring back to us.
Gemological tools come with instructions.
Gemological tools have not normally come with instructions because they were sold to professionals , but they do now! has listened to our customers, and recognizing the strong interest from the public in this fascinating field, we are including brief and concise instructions with our gemological instruments.
Gemological tools are easy to use.
Just like riding a bike (for the very first time.) Most tools take some diligent reading and some generous patience. Refractometers are easiest, then dichroscope, polariscope and much farther down the line is the spectroscope.
Only diamond can scratch glass.
Any gem material harder than glass at Mohs 5.5, can scratch it, quartz, tourmaline, topaz, garnet, sapphire, etc.
Diamonds are unbreakable.
Diamonds are very breakable, due to their cleavage plane. If struck along the cleavage plane and diamond can easily shear off along the plane and leave you with two diamonds!
Opals and pearls make great rings.
Opals and pearls are soft and will abrade over time in a ring which takes heavy wear.
Diamonds are always worth more than other gemstones.
The value of diamonds is currently maintained by a cartel that restricts supply. Because diamonds are as common as tourmalines, they would be worth as much as tourmalines if supply were unrestricted.
WANTED: One gemological tool to identify them all.
I want one too! An appropriate identification requires multiple tests and even more tests are required to distinguish natural gems from synthetics.
Gemstones can be identify from a photograph.
This has been attempted and requested many times! It is woefully inaccurate and lots of fun.
Must use GIA tools to get Graduate Gemology degree from GIA.
No, you can use any gemological tools available to get your degree. We offer a value-focused, high quality alternative to the brand-focused high priced products from GIA.