The Sapphire Buying Guide – Quality Factors, Treatments & More!

The Sapphire Guide

Whether you are buying a Sapphire for an engagement ring or an anniversary, birthday or christmas present, you want to know that you are buying a stone that is of good quality.

In this guide to buying a Sapphire, I am going to keep it focused on the Blue Sapphire as this is the most popular colour when it comes to a Sapphire but much of the information can be applied to all of the colours that you can get in a Sapphire.

What is a Sapphire?

It is always useful to understand a bit about a gemstone before you go and buy one, so here is a little bit of information about Sapphires.

  • Sapphires are part of the Corundum family and are the sister gemstone of Ruby
  • Sapphires measure 9 on the Mohs hardness scale. This means that Sapphires are more resistant to being chipped or scratched than nearly all other gemstones except for Diamonds.
  • This combination of good durability and hardness means that Sapphires are ideal for use in any type of jewellery and are a great alternative to diamonds for engagement rings.
  • Birthstone Month: September
  • Anniversary: 45th

Quality factors that affect the price of a Sapphire


Clarity is how free from inclusions the stone is and ideally you want as fewer inclusions in your Sapphire as possible and there are a few reasons for this:

  • They will look cleaner to the naked eye and thus more appealing, these are often referred to as ‘eye clean’ stones.
  • Heavily included stones will impact the transparency of the Sapphire and can lead to them being translucent or opaque, rather than the ideal transparent.
  • Fractures and other inclusions (such as two-phase and crystal inclusions) can cause potential durability issues, especially when when exposed to heat such as a jewellers torch.

Not all inclusions are bad in a Sapphire though and some can be used to identify the origin of the stone and also whether or not it has been treated. Some of the inclusions (other than those mentioned above) can include:

  • Silk – lots of small rutile needle inclusions that give an appearance similar to that of a piece of silk (mostly found in stones that haven’t been heat treated)
  • Fingerprints – the are partially healed fractures with a Sapphire and can be found in both untreated and heat treated stones
  • Angular Colour Zoning – these are areas of colour concentration, from colourless/near colourless to strong blue within the stone and are produced when the crystal grows.
Colour Zoning in Sapphire. Img Credit – Gem-A

Star Sapphires

While the majority of time, most people will be looking for an ‘eye clean’, transparent Sapphire, there is one exception to the rule!

And that is Star Sapphires, which are heavily included, opaque Sapphires that show a phenomenon known as asterism, which you can clearly see in the GIA picture.

The Asterism is caused by lots of rutile needles within the stone that follow the growth structure of the natural crystal and when the stone is cut properly, the light reflects off these inclusions to cause the appearance of the star.

These are highly desirable amongst collectors.


Possibly the most important factor when assessing the quality of a Sapphire is the colour and the quality of the colour as this has a big impact on the price of the stone. Ideally you want a colour with good hues and saturation, with the colour to be evenly distributed across the stone.

Colour Quality Blue Sapphire

The quality of the colour in blue Sapphires can vary quite a lot, as you can see in the image above.

  • The stone on the left is very dark and appears black when looking down through the top of the stone, it also has an opaque appearance (no light passing through the stone)
  • The middle stone has good clarity and transparency but the stone is a pale blue colour, this is a much better quality than the stone on the left but still not the most desirable.
  • The final stone is a fine gem quality Sapphire, it has good clarity and transparency but also possesses a very desirable deep, rich blue colour.

The most desirable colour in blue Sapphires is either Kashmir, Royal or Cornflower blue and these attract the highest premiums, especially if the colour is natural.


As with all gemstones, the larger the stone, generally the higher the price as they are rarer than smaller sized stones.

With blue Sapphires, it is not unusual to see good quality stones up to 3 carats in weight, this is due to how the natural crystals grow.


Due to the excellent toughness and high level of hardness, Sapphires are suitable for all types of cut style but larger stones are generally cut to either Oval or Cushion cuts as these produce a better yield from the rough crystal than other styles.

With smaller stones, usually 1 carat or less, it is not unusual to see Sapphires cut into a variety of different cuts, including round and square.

To really bring out the colour in the stones, good quality Sapphires will generally have quite a deep pavilion and will often require a custom made mount to accommodate for this.


It is estimated that over 90% of the Sapphires for sale at any given time have been treated or enhanced in some way. However, not all treatments are the same and while some are industry accepted, some are not and can have a negative impact on the value of the stone.

Heat Treatment

Sapphires have been heat treated for hundreds of years and all it involves is heating the stone up to a certain temperature in a controlled environment to either increase or decrease the colour of the stone.

The treatment is perfectly fine and is similar to what happens to the Sapphires in nature, the results of heat treatment are stable and the colour won’t change over time.

Glass or Fracture Filling

Glass filled Sapphires are something you really want to avoid as they are really low quality stones that have been filled with a high lead content glass to reduce the appearance of fractures.

Honestly best avoided as the glass can be removed from the stone if exposed to heat or chemicals and in some cases the removal of the glass can cause the stone to break into pieces.

Treated and Synthetic Sapphires
Heavily Treated and Synthetic Blue Sapphire

Synthetic Sapphires

One of the biggest factors when it comes to the value of a Sapphire is whether or not the stone is natural.

Natural stones are far more desirable and all but the poorest quality natural stones will be more valuable than their equivalent synthetic. A natural stone can be identified in a few ways such as the presence of inclusions and angular colour zoning (as seen above).

Synthetic stones will also have a very uniform colour and under 10x magnification, curved growth lines will be visible in the pavilion of the stone.


Following on from the point above, the origin of the Sapphire can have a big impact on the value of the stone. The most desirable of all the locations is Kashmir but only small amounts of fine gem quality Sapphires that came out of the region, this means that a Kashmir Sapphire can be very expensive.

The next most desirable locations for blue Sapphires are Ceylon (Sri Lanka) and Burma (Myanmar). Even though locations affect the sale price, my advice is to always choose a good quality stone over where it came from.

Lab Reports

A lab report from a reputable lab such as GIA or SSEF will add value to an Sapphire if it states it is a natural and has been treated. A report is especially important when a location or lack of treatment is specified by the seller.

FAQ Sapphires


There are lots of factors that impact the value of a blue Sapphire. But as obvious as this may sound, one of the most important factors is whether or not you like the look of the stone.

There is no point buying one that the person selling the stones says ‘is better quality’ or the one your friend or partner thinks is nicer. At the end of the day it is you that is going to be wearing it so choose the one that attracts your eye.

It may not be perfect on paper or in the eyes of experts but if it perfect to you, then that is all that matters.

I hope some of the tips in this post will help you when you go to buy your perfect Sapphire. If you have any questions about buying a Sapphire then please feel free to get in touch.

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