Ruby

Ruby is a red sapphire. They are both the same mineral, both are corundum, with similar properties. 

Ruby quality and cost are based on its colour. Cut and clarity are factors but in fact, the most desirable and expensive rubies are a little cloudy. Prices increase dramatically as carat weight increases as larger rubies are rarer than larger sapphires and most other very precious gems. 

The brightest and most valuable shade of red is historically called pigeon blood red which is a pinkish vibrant red. In Australia, the more popular colours in the past were fire engine to brick red but at Holloway Diamonds we have noticed a trend to more intense and saturated pinkish-red colours.

Ruby is the birthstone for July and is equal to second hardest (along with sapphire) to scratch after diamond with a designated Mohs hardness of 9. Ruby and sapphire are harder to break than diamond and much tougher than emerald. 

The brightest rubies are those that are very strongly pink-red fluorescent in ultraviolet light. Not all sources of ruby fluoresce but the bee’s knees are those from Burma or Myanmar as it is now known.

Australians tend to spend a fair bit of outdoor time and our cities have more clear sky days than most other big cities. So fluorescence in rubies is a bonus. 

Most rubies (and sapphires) are cut and polished into ovals and cushions because of the barrel-shaped nature of rough corundum crystals. Large rounds and emerald cuts can cost a lot more than ovals. 

Like emeralds, natural rubies are more inclined than most gems to have a lot of inclusions. Rutile needles known as “silk” and other cloud-like inclusions can be a great benefit. Slightly cloudy hazy rubies show up as ‘red on red’ and can appear more beautiful in many types of lighting whereas crystal transparent rubies may appear darker and deeper in poor lighting. Gemmologists use inclusions found in natural rubies to distinguish them from synthetics and imitations. Almost all rubies are heat treated, often in rough form before cutting to reduce the impact of inclusions and make the gems more transparent. Untreated rubies can be identified by the unheated nature of inclusions. They command a large premium overheated rubies and are usually sold with a lab report from a respected gem lab.

The boundary between rubies and pink sapphires is a funny turn of events. Decades ago dealers would offer pink sapphires as rubies because rubies were more valuable. Today top vibrant pink sapphires are more valuable than rubies and lower grade pinkish rubies are often promoted as pink sapphires.

Sapphire

Sapphire is a ruby of any colour other than red. Blue is the most common and most well-known, but yellow, pink, purple, orange, yellow and green are also precious and beautiful.

The most desirable blue sapphires are strongly saturated in mid-tones. The most desirable of these have historically been the almost mythical Kashmir sapphire that is slightly hazy intense blue that becomes ‘blue on blue’ because it is slightly opaque and appears blue in many different lightings. 

Like rubies, Australians have moved away from darker blue sapphires to more mid-tones and more saturated blues. Historically Australia was the world’s largest source of deep dark blue sapphires. 

Most sapphires (and rubies) are cut and polished into ovals and cushions because of the barrel shaped nature of rough corundum crystals. Large rounds and emerald cuts can cost a lot more than ovals. 

Sapphire is the birthstone for September. 

Sapphire is one of the two gem-varieties of corundum, the other being ruby (defined as corundum in a shade of red). Although blue is the best-known sapphire color, they occur in other colors, including gray and black, and they can be colorless. A pinkish orange variety of sapphire is called padparadscha.

Australia is still a major source but the most valuable sapphires and collectors’ favourites today are from Burma and Sri Lanka. Other primary sources are Thailand and Laos with more recent sources of Madagascar and East Africa.