Ruby Gemstone Guide

What is a Ruby?

Ruby is the red variety of the mineral corundum, one of the hardest naturally occurring minerals on Earth. Corundum is composed of aluminium oxide and forms in a range of colours. When corundum appears red, it is classified as ruby. All other colours of corundum, including blue, pink, yellow and green, are known as sapphire.

Ruby and sapphire therefore belong to the same mineral family, distinguished only by colour. This shared origin means that ruby possesses the same exceptional durability and brilliance that makes corundum gemstones so highly valued in jewellery.

What Gives Ruby Its Red Colour?

The red colour in ruby is caused by the presence of chromium within the crystal structure. Chromium replaces some of the aluminium atoms in corundum, absorbing certain wavelengths of light and reflecting red.

The intensity and tone of red can vary considerably. Ruby colour ranges from pinkish-red through to deep, vivid red and even purplish-red tones. The concentration of chromium, along with the presence of other trace elements such as iron, influences the final appearance of the stone.

The boundary between ruby and pink sapphire is not universally defined. Terminology and classification can vary between gemstone laboratories, trade organisations and geographic markets, so it is important to understand that the distinction is not absolute.

Ruby Colours and Appearance

Ruby colour is evaluated based on three main characteristics: hue, tone and saturation. Hue refers to the primary colour, which in ruby is red, though it may lean towards pink, orange or purple. Tone describes how light or dark the colour appears, and saturation refers to the intensity or purity of the colour.

The most highly valued rubies typically display a vivid, pure red with strong saturation and medium to medium-dark tone. However, personal preference plays an important role, and many people appreciate rubies across the full spectrum of red tones.

As mentioned, the classification of very pale red or pink corundum can vary. Some laboratories and markets classify lighter pinkish-red stones as pink sapphire rather than ruby. There is no single, universally accepted dividing line, so it is helpful to understand that terminology may differ depending on the source.

How Hard and Durable is Ruby?

Ruby scores 9 on the Mohs scale of mineral hardness, making it one of the hardest natural gemstones. Only diamond, which scores 10, is harder. This exceptional hardness makes ruby highly resistant to scratching and well suited to everyday wear, including in rings and engagement rings.

It is important to note that hardness refers to a gemstone's resistance to scratching, not to breaking or chipping. While ruby is very hard, it is not completely immune to damage. A sharp blow or impact against a hard surface can still cause chips or fractures, particularly if the stone has existing inclusions or structural weaknesses.

With appropriate care and sensible handling, ruby jewellery can be worn regularly and passed down through generations.

Where Are Rubies Found?

Rubies are mined in several countries around the world. Historically significant sources include Myanmar, which has produced rubies for centuries and is known for stones with rich, vivid red colour. Other important sources include Mozambique, Sri Lanka, Madagascar, Tanzania, Thailand and Vietnam.

Each geographic source can produce rubies with distinctive characteristics, though there is considerable variation within any single location. Geographic origin alone does not determine the quality or value of a ruby. A well-cut, vivid ruby from Mozambique, for example, can be just as beautiful and valuable as one from Myanmar.

Origin may be noted on gemstone reports and can influence price in certain markets, but the most important factors remain the stone's colour, clarity, cut and overall appearance.

Natural, Treated and Lab-Grown Rubies

Natural Ruby

Natural ruby forms over millions of years under specific geological conditions. Natural rubies are mined from the earth and may or may not be treated to improve their appearance.

Laboratory-Grown Ruby

Laboratory-grown rubies are created in controlled environments using processes that replicate the natural formation of corundum. These rubies have the same chemical composition, crystal structure and physical properties as natural rubies, but they are produced in a matter of weeks or months rather than over geological timescales.

Laboratory-grown rubies are typically less expensive than natural rubies of comparable size and quality. They should always be clearly disclosed as laboratory-grown or synthetic.

Heat Treatment

Heat treatment is widely used in the ruby trade to improve colour and clarity. The process involves heating rough or cut rubies to high temperatures, which can dissolve certain inclusions, improve colour saturation and enhance overall appearance.

Heat treatment is stable and permanent, and the vast majority of rubies available today have been heat-treated. Untreated rubies with fine colour and clarity are rare and typically command premium prices.

Other Treatments

Some rubies may receive additional treatments, such as fracture filling, which involves filling surface-reaching fractures with glass or resin to improve clarity. Fracture-filled rubies require special care, as the filling material can be damaged by heat, ultrasonic cleaners or certain chemicals.

All treatments should be disclosed appropriately by sellers, and gemstone laboratory reports typically note the presence and type of any treatments detected.

What Determines Ruby Quality?

Ruby quality is assessed using several factors, often referred to as the "Four Cs" plus additional considerations:

Colour

Colour is the most important factor in determining ruby quality. The most desirable rubies display a vivid, pure red with strong saturation and good tone. Stones that are too dark or too light, or that show strong secondary hues such as brown or orange, are generally less valued.

Clarity

Clarity refers to the presence of inclusions or internal characteristics. Most natural rubies contain some inclusions. Rubies with fewer visible inclusions and better transparency are generally more valuable, though some inclusions are accepted and even expected in natural stones.

Cut

A well-executed cut maximises a ruby's colour, brilliance and overall appearance. Poor cutting can result in uneven colour distribution, reduced brilliance or visible windowing. Skilled cutting is essential to bring out the best in a ruby.

Carat Weight

Larger rubies are rarer than smaller ones, and price per carat typically increases with size, particularly for stones with fine colour and clarity. However, a smaller ruby with exceptional colour and clarity can be more valuable than a larger stone of lower quality.

Treatments

The type and extent of treatment can significantly affect value. Untreated rubies with fine colour and clarity are rare and command premium prices. Heat-treated rubies are widely accepted and represent the majority of the market.

Origin

Geographic origin can influence price, particularly for rubies from historically significant sources such as Myanmar. However, origin is secondary to the stone's intrinsic qualities.

No single characteristic determines overall quality. A ruby should be evaluated holistically, considering all factors together.

Ruby Inclusions

Natural rubies commonly contain inclusions, which are internal characteristics formed during the stone's growth. Inclusions can include mineral crystals, fractures, colour zoning and needle-like structures known as silk.

Some inclusions can provide evidence of natural formation and may be examined by gemologists to help determine origin and treatment history. However, not every inclusion proves authenticity, and laboratory-grown rubies can also contain inclusions.

The visibility and impact of inclusions vary. Minor inclusions that do not significantly affect transparency or durability are generally acceptable in natural rubies. Heavily included stones with reduced transparency or structural weaknesses are less desirable.

Ruby in Jewellery

Ruby's exceptional hardness, vivid red colour and enduring appeal make it a popular choice for a wide range of jewellery, including rings, engagement rings, earrings, necklaces, pendants and bracelets.

The durability of ruby makes it particularly well suited to rings and other pieces that are worn frequently. Ruby engagement rings have become increasingly popular, offering a distinctive alternative to diamond.

Ruby pairs beautifully with a variety of precious metals, including yellow gold, white gold, rose gold and platinum. The choice of metal can influence the overall appearance, with yellow and rose gold complementing the warm red tones of ruby, whilst white gold and platinum provide a cooler, more contemporary contrast.

How to Care for Ruby Jewellery

Ruby is a durable gemstone, but appropriate care will help maintain its appearance and longevity.

Routine Cleaning

For most rubies, gentle cleaning with lukewarm water, a small amount of mild soap and a soft brush or cloth is suitable. Rinse thoroughly and dry with a soft, lint-free cloth.

Ultrasonic and Steam Cleaning

Ultrasonic and steam cleaners can be effective for some rubies, but they are not suitable for all stones. Rubies that have been fracture-filled, heavily included or treated with certain processes may be damaged by these methods. If you are unsure about the treatment status of your ruby, it is advisable to seek professional advice before using ultrasonic or steam cleaning.

Storage and Handling

Store ruby jewellery separately from other pieces to avoid scratching softer gemstones or metals. Avoid exposing ruby jewellery to harsh chemicals, extreme temperatures or sudden impacts.

Professional Inspection

Periodic professional inspection and cleaning can help identify any loose settings, worn prongs or other issues before they result in damage or loss.

Ruby Meaning and Symbolism

Throughout history, ruby has been associated with a range of symbolic meanings and cultural beliefs. Traditionally, ruby has been linked to love, passion, courage, prosperity and protection.

In many cultures, ruby has been regarded as a stone of vitality and strength, and it has been worn by royalty and warriors alike. These associations are rooted in historical and cultural symbolism rather than scientific evidence.

It is important to note that any claims regarding healing, medical or supernatural properties of gemstones are not supported by scientific evidence. The value and appeal of ruby lie in its physical beauty, durability and cultural significance.

Is Ruby a Birthstone?

Yes, ruby is the traditional and modern birthstone for the month of July. Birthstone traditions vary by culture and region, but ruby has been consistently associated with July in both historical and contemporary birthstone lists.

Ruby jewellery is a popular gift for those born in July and is often chosen to mark birthdays, anniversaries and other special occasions.

Ruby vs Sapphire

Ruby and sapphire are both varieties of the mineral corundum. The distinction between them is based solely on colour. Red corundum is classified as ruby, whilst corundum in all other colours, including blue, pink, yellow, green and orange, is classified as sapphire.

Because they share the same mineral composition, ruby and sapphire have identical hardness, durability and crystal structure. The only difference is the trace elements that produce their respective colours.

As noted earlier, the boundary between ruby and pink sapphire is not universally defined, and classification can vary between laboratories and markets.