Gem Ruby has been the main stray of the jewellery industry for centuries. It has been always the first love of gemologists, gem dealers, collectors and the customers. From the ancient times, Rubies are gems of the wealthy people. The demand for the Rubies has usually much higher than its supply. The main reason for the shortage in supply of Rubies is the depletion of corundum reserves of Thailand, Cambodia and Mogok in Burma. This leads to shoot up of the prices of Ruby much above the expectations of any one.

To be able to deal with the problem of high prices of Ruby, a group of gemstone experts and scientists came up with idea of producing Synthetic Ruby. In the past, Synthetic Rubies were considered as low cost Ruby. These Synthetic Rubies are real Rubies (as they are made up of aluminum oxide). But, they are created in the laboratory under the process known as “Flame-fusion”. The Rubies produced under this method are attractive and has very low value in the market.

In November 2004, the Gemstone Industry witnesses a large number of Rubies having some uncommon features entering into the market. After the detailed investigation of these gemstones by the recognized laboratories like Asian Institute of Gemological Sciences Gem Test Laboratory (AIGS) and Gemological Institute of America (GIA) they concluded that Rubies are Glass filled Rubies.

Treatments for enhancement of Rubies: There can be two types of treatment given to Rubies for the enhancement.

 1.Conventional Heat Treatment: Heat treatment can improve the color and blemishes of the stone. This treatment is commonly used for the lower quality of Ruby rough stones to remove purple tingle, blue patches and silk. Generally, this treatment occurs around the temperature of 1800 degree Celsius (3300 degree Fahrenheit). Besides this, some Rubies undergo a process of low tube heat, in which stone is heated over charcoal for the temperature of about 1300 degree Celsius (2400 degree Fahrenheit) for 20 to 30 minutes.

2.Lead Glass filling Treatment: Lead glass filling is a treatment given to the low qualities of Rubies. It is a process under which fractures inside the Ruby are filled with lead glass (or a similar material) at considerable temperature which dramatically increases the transparency and color of the stone. The refractive index of Rubies and lead glass is almost same which allows light to pass through the gem as a result color and clarity improves.

Glass filling treatment for Rubies was discovered at Gem laboratory in Chantapuri, Thailand under the expert Mr. Mahiton Thondisuk.

Process of Glass Filling:Lead glass filling is a multi-step treatment which involves simple heat treatments and then use of different lead rich compounds to fill the fissures and cavities of the stone.

Step 1: The stones are pre-polished to eradicate all the impurities that could disturb the treatment. The rough is cleaned by hydrogen fluoride.

Step 2:The second step is a “warming” step. At this step, heat treatment is given to the stones to remove the impurities inside the fissures which could disturb the treatment when the glass is added. The heat temperature can be given from 900 degree Celsius to 1400 degree Celsius. But, generally treatment is done around the temperature of 900 degree Celsius. It is believed by AIGS (Asian Institute of Gemological Sciences) that at 900 degree Celsius the rutile inclusions within the stone will not melt and as a result stones will have that aspect of “unheated” stones maintained in them.

Step 3:The third step includes heat treatments of the stone with some oxide powders. The composition of these oxide powders may consists a mixture of  lead, silica, sodium , potassium, calcium and metallic oxides like vanadium and bismuth are also added in some glass compositions. There are two main types of glass compositions used in the process.

First type:The first type of composition is a basic formula which is a simple lead rich transparent glass. This formula is usually used for most of the best quality larger stones. The orange powder will turn into a yellowish to orange glass after heating.

Second type: The second type of composition includes some other metallic oxides in order to produce the glass, optimizing the color and other aspects of Rubies. This formula is famous by the name “Popular Formula” and it is used on “iron stain” rich commercial quality stones. This formula is a mixture of many oxides which results into pink color. Under, this formula heat treatment temperature is slightly higher around 1000 degree Celsius.
The rubies are dipped with oils, then covered with the powders and embedded in the electric oven at the temperature of 900 degree Celsius for one hour in an oxidizing atmosphere. The powder will fuse during the heating process and turns into the glass.

This third step of heat treatment can be performed repeatedly three to four times with different metallic oxides in order to get desired and better colors. Then, the stones are finally cut and polished.

Difference between Glass-filled, Heat-treated and Unheated Rubies:

1. Prices of the Ruby gems with glass filled treatment are comparatively low to those who are heated with the conventional heat treatment method. Unheated Rubies are those which are not heated at all command very high prices.

2. There is a lot of difference in the inclusions of these three types of Rubies. The difference will be explained by the following pictures:

3. Glass filling of fractured Rubies is a post concept while conventional heat treatments have been given to Rubies from the centuries.

4. The intensity of heat treatment is high in conventional heat treatment as compared to glass-filled method.

Disclosure of the Treatments: All ethical sellers should disclose any treatment given to the gemstones at the time of selling it to customers. As per AIGS (Asian Institute of Gemological Sciences) opinion “as long as the customer is provided with the correct information of the stone and price charged to him is related to the real quality of the stone there is nothing wrong about the treatments”.

In fact, the dealer should provide the difference between Natural Ruby and Glass-filled Ruby to the customer. He must be acknowledged about the splendid qualities of Natural Ruby at the time of purchase.

Trend of Glass-filled Rubies: Following are the features of Glass-filled Rubies which increases its demand in the market:-

1. High prices of Natural Ruby: Glass-filled Rubies are very reasonably priced. They are less than 2% of the price of the Natural Rubies. Glass-filled are easily available in the market at a price of 2$-10$ per carat. While, Natural Rubies with average quality ranges between 200$-500$ per carat.
2. Good Color: The color of Glass-filled Rubies is also fine because its fractures and cavities are filled up by lead and other metallic oxides. These repairs give Glass-field Rubies a good transparency and also a good color.

3. Satisfaction to the customer:Glass- filled Rubies gives satisfaction to the customer. For example: if a customer buy wants to buy a Natural Ruby costing him 100,000$ but cannot afford it then he can switch to Glass-filled Ruby costing him around 100$. Customer can buy glass-filled Rubies and feel that at least there is some content of Ruby in these Glass-filled ones at much cheaper prices.

4. Appropriate for mass production: Glass-filled Rubies can be mass produced for the bulk orders. It is very easy to produce same color, same size of Rubies in case of glass-filled ones. At the same time, it is impossible to make Natural Rubies in perfect calibrated sizes and shapes.

5. Change in fashion: Bold statement pieces of jewelry is the trend of   today and red is the color which would always be in demand. The prices of large size natural Rubies are sky-high so customers are shifting towards glass-filled Rubies which are available at much reasonable prices.

6. Easy to trade: Glass filled ruby are profitable also. Thatswhy, everyone is buying and selling this stone. It is very easy to sell it to any customer who wants to buy Ruby. Most of the dealers buy these to make sure that if a customer comes in their store looking for Natural Ruby but does not want to spend 20,000$ on a 10 carat stone then they would usually return back and walk of their store. But if they have glass-filled ruby then they can sell it for 2000$ and make good profit and convince the buyer that this is still Ruby just that it has glass content filled by humans in it.