How to select Ruby

Jewellery Rubies is one of most intrigue and speculative areas of human history till our days. Rubies, one of the four precious gemstones alongside diamonds, emeralds, and sapphires, are highly valued for their striking red colour and remarkable durability.

All over the time people intentionally or mistakenly mixed rubies with some other stones. There are quite a few remarkable misleading of rubies authentication in a history. One of the prominent one is Black Prince's Ruby in The Imperial State Crown.


The large red gemstone in the crown - known as the Black Prince's Ruby. It is thought to have been worn in 1415 during the Hundred Years' War by Henry V at the Battle of Agincourt - when English forces beat the French to the south of Calais.
In fact The Black Prince's Ruby is a large, irregular cabochon red spinel weighing 170 carats (34g) set in the cross pattee above the Cullinan II diamond at the front of the Imperial State Crown of the United Kingdom.

Ironically we can see the similar situation in The Imperial Crown of Russia. The beautiful crown is adorned with 4936 diamonds arranged in splendid patterns across the entire surface of the crown. Bordering the edges of the "mitre" are a number of fine, large white pearls. The crown is also decorated with one of the seven historic stones of the Russian Diamond Collection: a large precious red spinel weighing 398.72 carats (79.744 g), which was brought to Russia by Nicholas Spafary, the Russian envoy to China from 1675 to 1678. It is believed to be the second largest spinel in the world.


The large remarkable spinel is placed above of 5000 diamonds. Obviously such red stones valued very high in that time. People could call bright red sparkling stone as a ruby.

While developing skills, techniques and methods of analysis we can distinct now ruby, spinel, tourmaline and other stones with the similar optical and physical characteristics. Large ruby stones above 100 carats are extremely rare. There are just a few known examples in the world on natural rubies above this size. That is why spinel was used as a bright red stone decorating the most beautiful crowns.

Ruby is one of the most popular decoration stones in modern jewellery emphases. Quality rubies are quite expensive and a typical price can be around a few thousand dollars per carat. It can be very tempting to sell less precious mineral for a higher price though. It happens very often and you have to be at least aware of that.

The most generic advices how to avoid ruby fraud refer to respectable certification and authentication. That is absolutely true. Only the properly issued certificate can guarantee that you are dealing with the right natural stone. Of course it could be issues with certificates themselves but it is a different story.

However you can see that some rubies are offered for more or less reasonable or even relatively low price. What is the difference and why it happens?
The availability of quality minerals including rubies is generally decreases in time. That is why those minerals are chosen as a precious stones that at least can hold their price for years if not forever. Many ruby deposits like well known in Burma are practically exhausted now. Regardless a few new fields were recently discovered in Africa they can't satisfy growing market demand with a quality minerals.
Nevertheless availability of lower quality rubies is quite high. They are not perfect to make a jewelry right after they extracted but a few techniques can make it possible.

Enhancing Ruby Appearance

There are few methods to enhance natural ruby quality. Some of them have been used for centuries and nothing is wrong with them. It is a heating of rubies. The proper heating allows to improve transparency of stone and eliminate some unwanted inclusions.
There are at least three different levels of heating: minor, moderate and significant. Minor is what can generally happen in nature like heating up to a few hundred degrees of Centigrade.




All ruby experts agree that the most majority of rubies in the market are heated ones. The opinion can be different if it is 95%, 99% or even 99.9% are heated rubies in contemporary market. The chance to find unheated natural ruby is extremely rare in these days. Even though the ruby is known to be heated its price depending on other factors can be $5000-$10000 per carat or more. Significant heating that can be up to corundum melting point 2040 degrees can dramatically change the crystal structure of a mineral but not much the chemical content of a stone.

Experienced gemologists can distinct heated rubies from natural untreated while inspecting them under a microscope. Their decision is based on the presence and character of inclusions that can always be found in natural rubies.


Authentic natural rubies often exhibit visible inclusions, known as "silk", which are characteristic of their organic origin. These internal features add to the gem's allure and authenticity.

Heated rubies may appear more homogeneous in appearance, with fewer visible inclusions. The heat treatment process can diminish the presence of natural imperfections, resulting in a gemstone with enhanced clarity and colour.

The actual difference between heated and unheated rubies may not be so dramatic. Generally heated rubies are a bit brighter than unheated however low quality stones are often muddy and dull.

Flux Healing of Rubies

The next level of treatment is a flux treatment. It is a treatment that has to brings in contact with the material and it will lower to lower the melting temperature of the ruby. A substance such as borax is being added in. This improves the clarity of the ruby. However, because the materials being added in are not natural, the price of flux treatment ruby will be less.


Flux-healed fracture in a ruby that was heated with borax flux.

Glass Fill Rubies

The next and more aggressive step of ruby treatment is glass fill. The glass fill most important issue is in the market is the lead glass filling of fractures in rubies they are more browny and opaque. The lead glass-filled ruby made the appearance of the ruby to be transparent and cuttable, which is easily broken. With training and microscope, it will enable people to see the properties of its glass lead ruby. Glass lead glass-filled ruby usually has a flash effect property which is a bright flash and structure of blue and orange fractures. Large Glass bubbles cavities and flattened gas bubble are also seen in lead glass-filled rubies.


Unlike minor to moderate heating of rubies is irreversible, glass filled rubies are sensitive to more or less aggressive chemicals even to household solvents and acids. It is how acid may affect the glass ruby surface. Before acid treatment.


Before acid treatment.


There are a lot of glass fill rubies sold on streets of Bangkok and Chanthaburi. Sometimes those stones are covered by oil to make them look more natural. The worth of those "rubies" is little to none so please don't mistake on it.

Other methods of Enhancing Rubies

Lately the most sophisticated methods of rubies treatment were developed. Diffusion of metals and expose to radiation are among of them. Those methods are more expensive compared to described before. Diffusion can be distincted by uneven colour and optical density through the stone under microscope. Experienced gemologist can easily detect such kind of treatment.

Irradiation of corundum varieties to change and enhance their colour is known since many decades but remains a difficult and challenging issue until today. The main reason for this is that natural radiation of a gem deposit may affect a gemstone over geological times in a similar manner to such a treatment, thereby naturally creating and activating colour centres in corundum.
Anyways, well equipped jewellery stores always check their products for excessive radiation. Thankfully, we had never had a chance to notice it among our products but we always check them just in case.

Conclusion

Don't be afraid of buying heated rubies. Majority if not all of rubies in the market are heated in these days.
Try to get a stone certificate from recognizable gemstone laboratory if you buy a jewelry for budget sensitive price. It is relatively easily to get a reliable certificate in Thailand, Sri-Lanka and similar countries specialized on gemstones production so don't neglect this opportunity if you are there.
It can be very costly to obtain it in Europe and North America though.

Don't hesitate buying affordable jewelry which looks beautiful, attractive and adorable to you. Quite often ruby manufactures don't have a chance to obtain certificate for each their stones but they are willing to sell them for less to avoid a very high competition in a higher price range level. Of course those rubies had undertaken some kind of enhancement. However it only make them more beautiful and attractive but for a much smaller price.
Just avoid buying glass fill rubies and synthetic rubies offered for a high price.




Nothing is wrong to buy a crystal clear synthetic stone assuming that you are aware of what you are doing and paying for. Synthetic rubies usually don't have typical for natural stones inclusions. They look very bright and transparent. However, low quality synthetic rubies are dull, have a purple tone and not transparent. You can distinct them easily even without a special knowledge and experience.

A good quality ruby attracts your attention right away. It should fascinate you how it looks but not how it costs. Get it and ware it if you love it no matter what other people say.