Tuesday, 5 August 2014

Common treatments for colouring gemstone beads. Should you be worried?

These days it’s common for natural gemstone beads to be colour enhanced. This is nothing new. In fact the practice goes back thousands of years. But is this something you should be worried about? Should you avoid enhanced beads or embrace them?

To answer this question you should first be aware of how stones are colour enhanced.

Perhaps the two most common ways are by dying and by heat treatment, and many gemstone beads on the market will have been treated in these ways.

Natural colour Carnelian
Stones, such as agate, are soaked in a dye that enters through the porous structure and leaves a colour change. Sometimes the dye can’t enter the more dense structure which leaves intermittent bands of dye and natural colour. This is most clearly seen in various dyed agates.

Dyed agates are actually quite easy to detect as the colours used are unnaturally bright. 

So, should you care if your stones have been dyed?

Firstly you should take care when purchasing dyed beads as the colour can sometimes run. And nothing ruins your day faster than a customer complaining that her favourite blouse has been ruined by the beads she bought off you!

Also beware that some dyes are not permanent and will actually fade when exposed to sunlight over a period of time.

Heat Treated Carnelian
A simple way to test if your beads have been dyed is to lick your fingers and then run them over the stones. Any residue dye will come off on your fingers. A better way is to rub nail polish remover over the beads to see if the dye comes off.

At BeadShopUK we actually make sure any dyed beads do not run once worn by soaking them in hot soapy water, and then soaking them in Acetone. Thankfully we've had no complaints so far (touching wood!)

The second most common treatment is exposure to heat. Certain stones can undergo drastic colour change when heated to a high temperature. The result can be a brighter colour or a deeper shade. Have a look at the Carnelian beads as an example.

Heat treatment is relatively stable and the colour change will last a long time. It’s also not possible to detect whether the stone has been treated with heat by nail polish remover.

Other modern methods for the treatment of gemstones include:

  • Bleaching – which is almost impossible to detect
  • Surface Coating – used mainly in the Gemstone industry on faceted stones
  • Fracture or Cavity filling – used mainly on precious stones (diamond, ruby, emerald) to improve clarity.
  • HPHT Treatment – High Pressure High Temperature, used on Diamonds
  • Impregnation - the surface of a porous gemstone is permeated with a polymer, wax or plastic to give it greater durability and improve its appearance. This is a common treatment for Turquoise beads, as without it the stone would naturally disintegrate with day to day use.
  • Irradiation - exposure of a gem to an artificial source of radiation to change its colour.

All good bead and gemstones suppliers should always disclose if the beads have been treated, but in reality many don’t. Sometimes it’s simply because they don’t know how the stone has been treated. Other times they prefer not to tell their customers.   

In the end however it's a matter of choice. Some customers prefer only natural colours and will avoid dyed stones like the plague. Others will be attracted to the variety of colours on offer and don't care that they have been treated. 

1 comment:

  1. Useful tips to be shared within your post for the treatment of coloring gemstones. Thanks a lot. Pancharatna gems Coimbatore | Kalpana Srikaanth