An introduction to Sapphires and Rubies

Introductie

The Corundum family: Sapphire and Ruby. - 12 minute read

Corundum is a mineral composed of aluminium and oxygen. In this basic composition, corundum is colourless. But colourless corundum is rare, usually there is a trace element in composition. These trace elements give the stone a colour.

If chromium is present in the stone, the stone becomes red (ruby). With lesser amounts of chromium, the stone becomes pink. If there is a minuscule amount of iron in it, the stone becomes yellow or green, and if titanium and iron occur together, the stone becomes blue. Vanadium causes the stone to turn purple. If va

nadium occurs together with chromium and iron, the stone becomes Padparadscha colour. It can also happen that the stone contains too many trace elements, in which case the stone often becomes opaque. Previously, it was not known that the basic composition of sapphire and ruby was the same and therefore two different stones were referred to. Hence, term ruby is used instead of red sapphire.

Localities

Corundum (sapphire and ruby) is found all over the world. The majority of the finds are of low quality and are therefore used in the industry for grinding and abrasives. An example of this are the sanding strips that are used in our studio. The beautiful gemstone quality sapphire that we sell in the shop is found in very few places, in very small quantities. One of the most important locations for sapphire is Sri Lanka. Sapphire has been found on this island for thousands of years. Most sapphires that are found are of a worthless quality and must first be (heavily) treated before they can be used in any way in jewelry. Beautiful untreated sapphires, above two carats, are very rare and stones with a good color without inclusions are found sporadically. These are called exceptional in the trade.

The demand for these untreated natural sapphires is many times greater than the quantity that is found, which is why the price always keeps rising. For this reason, natural untreated sapphires are a much better investment than treated ones. The location of a sapphire also has a great influence on the value of the stone. This is because different color and inclusion characteristics are known per location. The best quality comes from Kashmir, in second place is Burma and the third is Sri Lanka. The importance of the origin is relatively very important compared to many other stones. For example, with diamonds, the mine location is not a major factor at all.

It is worrying that people often blindly look and pay for the location without being critical about the color and quality of the stone. It is not an exact science to determine the mine location of a sapphire. Even the laboratory sometimes makes guesses. Almost the same stone characteristics occur at different mine locations. A recent study showed that as many as 50% of the gemstone laboratories surveyed had incorrectly determined the location. For this reason, many gemstone reports use vague terms such as ‘Characteristic inclusions that are commonly seen in …. sapphires’ and do not specifically mention the location. Those who do specifically mention a location are taking a greater risk.

Sapphire Treatment

Heat Treatment.

The oldest and most common treatment for sapphires is heat treatment. An estimated 95% of all sapphires on the market are heat treated. Heat treatment has three main effects:

1: It improves and enhances the color

2: It reduces color streaks and color zones

3: It improves clarity by partially dissolving certain inclusions.

Generally, pale sapphires are heated in a furnace between 1200-1600C until the inclusions dissolve and the color improves. This technique is relatively invisible after treatment and has no adverse effects on the stone.

Cutting the sapphire

The cut is something that receives almost no attention or consumer notice, but is essential for a vibrant, well-colored sapphire. In fact, a bad cut will ruin the most beautiful sapphire. Every cutter has the potential to cut a stone perfectly. However, he must make a trade-off between maintaining maximum weight and the best color. A piece of raw sapphire crystal almost never has an even color distribution. Often the color runs in bands or stripes, which makes the color better or worse depending on your angle. It is a complicated task to choose the right position and angle to start cutting. Once you have cut something off, you can't go back! Moreover, every sapphire is different to cut and therefore a project in itself.

In general, a well-cut sapphire is symmetrical and reflects light back to the viewer's eyes via its lower facets, maximizing the color and life of the stone. This is called internal reflection.

It is usually the case that a cutter will cut a sapphire a little deeper if the stone is a little lighter in color. This is done to keep the color as deep and intense as possible. The opposite happens if the stone is very dark. The cutter is then forced to cut the stone as shallow as possible to preserve the most beautiful color. If the lower facets of a sapphire are not cut at an angle enough, the light is not reflected properly and this light ‘leaks’ out of the stone. As a result, you can see right through the stone. This cutting error is therefore also called the window effect (internationally ‘window’). This spoils the intensity of the color and the liveliness in the stone.

Blue sapphire

The word 'sapphire' literally means blue in Latin. The blue in blue sapphire comes from the trace elements titanium and iron. The amount of titanium determines the intensity of the blue colour. So too little is not desirable but too much makes for a lifeless dark stone. The blue sapphire is the most popular and sought-after of all sapphire types. The blue sapphire has featured in royal jewellery collections for thousands of years and it is also often the first stone choice, even more often than diamond, for an engagement ring among noble families. Less sought-after than diamond, but well known to consumers. For this reason, blue sapphire, is often referred to simply as sapphire. Blue sapphire comes in colour variations from light blue, 'baby' blue to a deep royal blue.

'Cornflower blue'

A sapphire is often called 'cornflower blue' in the trade. So far, there is no definitive and internationally accepted way to clearly indicate what shade of cornflower blue actually is. This is because there are multiple shades of blue called cornflower blue. Some people believe it is a rich dark blue hue while others describe it as a softer, slightly lighter shade of blue. One thing is for sure, it is overused as a 'hype word' to increase the stone's value.

Locations of Blue Sapphire.

Blue sapphire is found in locations around the world, but there are only a few deposits that provide 'a lot' of high-quality blue sapphire. The most deposits have been known for thousands of years and it is rare that new mine sites are found.

1) Sri Lanka (Ceylon) & Madagascar.

The producer of the highest quality in numbers of sapphires is Sri Lanka. Before the country gained its independence from England, it was called Ceylon. In trade, stones from Sri Lanka are often still called 'Ceylon sapphire', as this is an old and accepted term that suggests added value. The only competition Sri Lanka has are the good quality sapphires that are found at new deposits in Madagascar. The colour shades and inclusions of Madagascar and Ceylon sapphires are often identical. Prices from my sites are also often similar.

2) Burma/Myanmar

Burma (now officially called Myanmar since independence from Britain) is a country where, for centuries, sapphires of a very high quality but in small quantities are found. The colour of Burmese sapphire occurs in a paler to a deep and intense blue, which is also called 'royal blue' colour. Many gemmologists, jewellers and auctioneers see it as an added value, when a high-quality blue sapphire comes from Burma. This is because for a similar quality stone from Sri-Lanka (Ceylon) half the price, or even even less is paid.

3) Kashmir (India)

'Kashmir' sapphires are seen as something mythical these days, and it seems like money is no object when buying a good quality Kashmir stone. At international auctions, fine quality stones of 2.50 - 3.50ct are auctioned for as much as €60,000 to €100,000+ per carat. Kashmir sapphires come from a hard-to-reach area in the Himalayan mountains in northern India, where they were found as early as the late 18th century. The stones were generally of exceptional quality. The term 'cornflower blue' is often associated with these stones. Terms like soft 'velvety' dark blue and deep 'sleepy' dark blue are also commonly used. The last working mines in this region were exhausted around 1920. As a result, Kashmir sapphires are extremely highly valued. They often sell for tenfold compared to similar stones from another country. A major problem is that Madagascar sapphires, very occasionally, look very similar to Kashmir sapphires. These stones have a similar colour, with similar inclusions. It has occasionally occurred that respected gemological laboratories identified Madagascar sapphire as Kashmir sapphire. Such misunderstandings naturally have major implications for the international auction houses involved. Such misunderstandings obviously have major consequences for the international auction houses involved.

Other localities

Blue sapphires also come from Thailand, Tanzania, Australia, Montana (USA) and Cambodia. These stones are fair to good quality, but the vast majority of stones from these locations require treatment before they can enter the market.

Pink Sapphires.

Pink sapphires were always very rare, occurring only in a few locations in: Vietnam, Sri Lanka and Burma. The recent discovery in 1990 in southern Madagascar, caused an unprecedented amount of pink sapphires to enter the market, rapidly increasing its fame and popularity. Madagascar is by far the largest supplier of pink sapphires and they range in a wide spectrum from pale pink, 'baby pink' to a deep magenta colour.

Yellow Sapphires.

About 98% of all yellow sapphires came from Sri Lanka (Ceylon).Other countries such as Australia, Thailand and Burma also supply some yellow sapphire, but in most cases with an obvious second colour in the stone. Recently, deposits have also been found in Madagascar, but so far these only produce smaller stones. Yellow sapphire comes in a wide spectrum from a pale yellow, canary yellow to an intense golden yellow colour.

Padparadscha sapphires.

The word Padparadscha (Pad-Para-dscha) is an ancient Sanskrit word that was used to describe the colour of the setting sun on a tropical lotus flower. Padparadscha sapphire is the rarest sapphire. Most consumers have never even heard of it. It is a very particularly beautiful stone and no other gemstone occurs in this unique colour combination of orange pink. These sapphires rarely come on the market and the buyers for these are collectors or enthusiasts who are actively looking for the right colour. The supply of beautiful, pure well-coloured Padparadscha sapphires is small, but the demand is very high, which is why the prices for these stones are extremely high. Padparadscha sapphires have come exclusively from Sri Lanka for thousands of years. Recently, other countries have found similar stones in Madagascar and Tanzania. Many experts and collectors believe that the term Padparadscha should only apply to these colour sapphires if they actually also come from Sri-Lanka (Ceylon) and show a colour distribution of 40 /60 combination pink and orange. In addition, stones from Tanzania and Madagascar often have the anomaly that a third brown colour is present in them.

Red-Pink and Red-Orange sapphires.

These are sometimes offered as padparadscha imitations. The stones are beautiful to look at and are seen by many as a subcategory of ruby and padparadscha. They can be precious despite an undertone of red running through the colour. In the past, the better labs would accept a small amount of red in the orange, or red in the purple, and were then still called Padparadscha. Nowadays, the rules have been tightened considerably at most labs and stones with a red-pink or red-orange colour are no longer called padparadscha by the better labs.

Star Sapphires

Star sapphires are cabochon cut sapphires with a star effect. People used to think the stone possessed magical powers that would protect the wearer. The star effect occurs because microscopic rutile needles in the stone, which lie on three

different directions, reflect light. The star is thus created by a phenomenon created by the reflection of light. This effect occurs only if there are enough needles in the stone and if the grinder has ground the stone in the right direction. The main location for star sapphire in almost all colours is Sri-Lanka. Only the padparadscha is almost never found in a star sapphire form. Burma is known for its beautiful deep blue star sapphires found there. Most good star sapphires have either a nice deep colour and a lesser star effect, or a lesser colour and a better star effect. With star sapphires that have both a perfect colour and a perfect star, chances are they are synthetic. Synthetic star sapphires are common, very cheap and have been made since the 1950s.

Lavender and Violet sapphires.

These stones come mainly from Sri Lanka and Madagascar. The colours range from a pale light lavender to an almost Tanzanite purple, and from a pale pale violet to a rich deep purple. These stones are almost never heated and are somewhat similar to Tanzanite, but with the advantage that the stone has the hardness of sapphire.

Colour-change sapphires

This phenomenon, also found in Alexandrite, causes the stone to turn purple under a lamp and blue in daylight. These stones are generally found in Sri Lanka and Tanzania. Recently, beautiful varieties have also been found in Madagascar. The colour-change effect is not always the same and the price also depends a lot on how strong the effect is. Stones with a small difference are cheaper than those showing 100% colour difference. Other colour combinations that are rarer are brown, red and green, and green to a yellowish green. The latter are rarer and mainly come from Tanzania.

Green Sapphire

These sapphires range from light lime to olive green in colour. They generally come from Sri-Lanka and Tanzania but recently new discoveries have been made in Madagascar. It is common for a second colour to be present with mostly yellow or blue as undertones.

Cognac sapphire.

Cognac sapphires have a very beautiful colour, which is generally very commercial. The variations are reddish brown or reddish orange. Cognac sapphires are most commonly found in Tanzania and Madagascar. These stones are most beautiful in the darker colour tones, the paler cognac sapphires possess little life. To reach its full potential, the cognac sapphire also depends on a good cut. Most cognac sapphires are natural and rarely treated.

Ruby

Ruby is a red variety of the mineral corundum. Its colour is caused by a small amount of chromium in its structure. This colour can vary from pink red to deep blood red. The colour of natural untreated ruby determines almost 70% of the price. The pure deep red variety known as 'pigeon blood red' is one of the most precious gemstones. Rubies over 5 carats in this colour are exceptionally rare and are priced at prices comparable to those of coloured diamonds.

Localities

The most famous locality for ruby is the Mogok valley in Burma. For centuries, this was the main location for ruby and the only location where pigeon blood rubies were found. Although ruby is still found in Mogok, as of the 1990s' most rubies come from the Mong Hsu region in Burma. Other important deposits include neighbouring countries Vietnam, Laos, Thailand, Cambodia, India and Sri Lanka. Furthermore, ruby is also found in Kenya, Tanzania and Madagascar.

Treatments

Most rubies (95%) undergo some form of heat treatment to enhance their colour. As with sapphire, this is generally accepted internationally. It is assumed that a ruby has always been heated unless it can be proven otherwise.

Lead glass-filled rubies.

A newer form of treatment that is flooding the market are lead glass-filled rubies. In their raw state, these stones are pieces of white-cream to dark red/brown corundum that are common as a by-product when mining for ruby and sapphire. These stones are placed in a bath of acid so that all the dark inclusions dissolve. This results in the stone becoming very porous and weak. The stone would break into pieces at the slightest amount of pressure. The stone is then placed in a kind of bath of liquid lead glass which restores its stronger structure and makes it beautifully transparent. These stones are then cut like a normal ruby. The average consumer will struggle to tell the difference between lead glass-filled 'rubies' and natural rubies.