Friday, 25 July 2014

History of treating and enhancing gemstones

Egyptian Hippo made from imitation Turquoise
Gemstone enhancement is not a new thing. Gems have been ‘improved’ through various methods for thousands of years.

The ancient Egyptians were the first at it. They were producing an imitation Turquoise called Faience before the pyramids were even built.

Pliny the Elder, who was a witness to the destruction of Pompeii two thousand years ago, noted that: “the Indians have discovered a means of counterfeiting gemstones, especially beryls, by colouring rock crystal.”

Meanwhile, the Stockholm Papyrus, written circa 300 AD, contains many recipes for dying gemstones and includes information on creating fakes and enhancing genuine gems.

Modern dyed agate beads
One ancient recipe to colour agate told that you had to first soak the stone in a sugar solution, keeping it warm for a couple of weeks, and then without washing it, bring the stone to boil in sulphuric acid. The result would be a more vibrant colour than was natural.

Closer to our time, Thomas Nicols wrote ‘The History of Precious Stones’ in 1653 and said that precious stones were often adulterated. He also noted that rock crystal could be coloured, but even in his day that was already an old practice.

These days we have quite a few methods for changing the appearance of stones -- we can bleach them, shower them in radiation, blast them with heat among other things. We might think this is a new thing, but actually it’s not!

But is it a good thing to ‘enhance’ natural stones? Are natural stones best? Do you even care that your gemstones have been treated? 

Monday, 14 July 2014

How are semi precious gemstone beads made?

The process of cutting and polishing gems is called lapidary. All gems are cut and polished by progressive abrasion using finer and finer grit.

Diamond, the hardest naturally occurring substance, is used to cut and polish the hardest stones.

The rough material is cubed, slightly larger than the required finished bead size, before being inserting into the Bead Mill.

Bead mills are used to grind and sand large quantities of beads simultaneously. They typically employ a grooved lap and a flat lap between which the beads are rolled and worn to shape. 

Silicon Carbide grits are used to shape the rough into round shapes. Different types of material require different grits, milling times, etc.

After shaping and sanding, beads are usually drilled and then polished by tumbling. Tumbling is turning large quantities of beads at a slow speed in a rotating barrel with abrasives and water for extended periods (days or weeks). 

By tumbling with progressively finer grades of abrasive (usually silicon carbide) and washing carefully between grades, the beads are gradually smoothed and polished. Tumbling barrels are often hexagonal in outline in order to enhance the stirring action of barrel rotation. An alternative to rotary tumblers is a vibratory machine, often called a vibratory tumbler, in which the containing barrel vibrates rather than rotates. 

The more stationary arrangement of vibratory machines makes it much easier to examine the progress of the stones inside, whereas standard tumblers must be halted in order to check progress.

Today, most semi precious gemstone beads are cut in standard round sizes – ie 4mm, 6mm. 8mm, 10mm etc.   Often there is a .5mm +/- tolerance in the finished size.  They are usually sold as 15” or 16” loose strung strands.

Semi precious beads are a natural material and therefore some natural inclusions, variations in colour and patterning are normal.  This is what makes them so exciting and why jewellery designers love to work with them.

Tourmalinated Quartz Beads

These beads are Tourmalinated Quartz. Aren't they stunning? 

 These stones are actually Silicone Dioxide with shards of Tourmaline needles running through them.

Tourmalinated Quartz are relatively common although a large quantity is produced in Brazil. These beads are completely natural, having formed under extreme temperatures that allowed the Quartz and Tourmaline to mix. 

These stones are believed to protect the wearer from negative emotions and thoughts, and are also used as a grounding stone to balance the mind.

You can buy some Tourmalinated Quartz beads at our online store. 

A brief history of beads

The name "Bead" comes from the Anglo Saxon word "Bidden" - to pray - probably from their use as beaded rosaries. 

For thousands of years beads have played an important role in every major culture throughout the world – as talismans in prehistoric and contemporary societies, as status symbols in the ancient world, as religious articles in the Buddhist, Christian and Islamic faiths and as a standard medium of barter throughout the world.

Semi precious beads have been around since before recorded history and before Christianity being used for ornament and trade.  The bead was probably the first gemstone to be cut by man and polished using sand as an abrasive.

One source refers to Indian literature dated about 2300 B.C. which refers to manikyam. Because mani is a term to describe a sphere or bead it concludes that some form of gem cutting was practised that early.