It was an informative and interesting presentation from Gary Smith, who provided the chapter with in-depth information and personal stories of his work as a Forensic Gemologist and dealings with the Pennsylvania department of weights and measures.
PA Gem Lab USA’s only forensic laboratory for jewelry/gemstones, and a metallurgical laboratory for Jewelers Vigilance Committee (JVC).
Gary’s store, Smith’s Jewelers is one of the few accredited laboratories in theUS. He has a vast knowledge of jewelry history and repair as a result of his training in Asia, Europe and theUS.
Noble Metals – Silver, Gold & Platinum
Silver, gold and platinum are referred to as “noble” metals because they are resistant to corrosion and oxidation. This resistance separates them from their baser brethren, at least in terms of durability. They tend to be precious, often due to their rarity in the Earth’s crust.
Platinum and gold can be dissolved in aqua regia, a highly concentrated mixture of hydrochloric acid and nitric acid, but silver cannot. Silver can dissolve in nitric acid.
Silver is having resurgence in jewelry due to the increased price of Gold as a commodity. Many jewelry lines have gone back to using silver.
Platinum became commercially viable as a metal for jewelry after 1900 with the introduction of welding technology which allowed melting of platinum.
Melting temperature of Silver – Gold & Platinum
Gold Trivia – A few trivial & fun facts about GOLD:
This guide is not so much about knowledge; rather it’s about a few little known facts and trivia about gold…something to bring up at a dinner party.
For instance did you know that….
ALL the gold ever mined would fill a cube approximately 20 meters x 20 meters x 20 meters.
One ounce of gold measures about 12mm x 12mm x 12mm or 1/2” x 1/2” x 1/2″. Tiny for the weight.
It is 19 times heavier than water. Lead is 11 times heavier than water.
A cubic foot of gold weighs about 1/2 ton. Just think about that for a moment. That’s the size of a ruler, cubed.
It is the 58th most abundant element on the Earth out of the 92 natural elements found.
1 ounce (31.1gms) of gold can be drawn into a wire 5 miles, that’s about 8 kilometers.
You can beat 1 ounce of gold to a sheet of over 160 square feet and that light would shine through that sheet. 1 gram can be flattened into a sheet 1 meter square.
That sheet of gold would be one hundred thousandth of an inch thick.
Historically a carat was a measure of weight based on the weight of a dried carob seed which in nature has a very consistent weight. The scientific name of the carob tree, derives from the Greek word kerátiοn, “fruit of the carob”.
The term Carat, the unit by which gem weight is measured, is also derived from the Greek word kerátiοn, the practice of traders in the Middle East was to weigh gold and gemstones against the dried seeds of the carob tree. The system was standardized, and one carat was fixed at 0.2 grams.
In Roman times, the pure gold coin of the realm at the time “the solidus”, weighed 24 carat seeds (about 4.5 grams). As a result, the carat also became a measure of gold purity. 24-carat gold means 100% pure, 12-carat gold means the alloy contains 50% gold, etc..
It has been estimated that 75% of the total historical world production of gold happened after 1910.
The word “gold” comes from the old English word “geolu” or “gelo” meaning yellow.
Chemically gold is almost chemically inert and is called a Noble Metal because of that fact. Very few chemicals can attack it, so that’s why it keeps it shine even when buried for 1000’s of years. Aqua Regis (Kings water) is an acid that will dissolve it. It is a mixture of concentrated Nitric and Hydrochloric Acids. There are a few Cyanide compounds that will also dissolve it and are used in gold refining. Trust Gary when he says, “you don’t want to go near either”.
Because of it colouring effect it is used to colour glass. Those lovely Ruby and Cranberry glass items you see owe their beautiful red to minute amounts of dissolved gold.
Yellow gold (eg 9K or 18K)…is produced using silver, copper, zinc & others
Rose gold…is produced using more copper or palladium and or zinc, & others
Green gold…is produced using more zinc & others
Blue gold…is produced using iron & others
Purple gold…is produced by using aluminium & others White gold…is produced using mainly nickel
The largest gold nugget known to be found was called “The Welcome Stranger”. Found in Dunolly,Victoria,Australia, weighed a massive 2280 troy ounces or 70 kilograms.
The largest gold nugget still in existence is “The Hand of Faith” also found near Dunolly. It weighs 875 troy ounces or over 27 kilograms. It is also the largest nugget ever found with a metal detector. Just imagine hearing your metal detector going of, then digging down and finding that baby.
Forensic Gemologists use much higher tech instruments these days than acid and scratching tools, to non-destructively test metals. Using X-ray Fluorescence Spectroscopy an expensive tool that takes an x-ray source bounced off a sample and measures its energy levels. Because every element has a unique set of energy levels, each provides a unique set of energy readings. This allows non-destructive measurement and identification of an items metal composition.
The Chapter members had a great time, as it was a pleasure to have this opportunity with Gary, his wife Helen, and two granddaughters with us during Gary & Helen’s 47th Anniversary.
Summary by: Charlie Marts
Photos by: Melanie Marts, G.G.