Home Knowledges How to Check the Purity of Ruby Gemstones: A Full Guide

How to Check the Purity of Ruby Gemstones: A Full Guide

by Madonna

Ruby gemstones have long been cherished for their exquisite beauty and rich symbolism. These vibrant red stones are not only visually captivating but also hold immense cultural and historical significance. However, with the growing demand for rubies, the market has seen an influx of synthetic and treated stones. As a result, accurately assessing the purity of a ruby has become increasingly important. In this guide, we will delve into the key factors that determine the purity of ruby gemstones and outline step-by-step methods to evaluate their authenticity.

What Color is Ruby?

Ruby gemstones are renowned for their captivating and intense red hue. The color of a pure and high-quality ruby is often described as a deep, vivid red, reminiscent of the rich and vibrant tones associated with the phrase “pigeon blood” red. This exceptional color is a result of the presence of chromium within the stone’s composition. Rubies that possess this distinct and intense red color are highly prized and sought after in the world of gemology and jewelry. It’s important to note that variations in hue and intensity can impact the value and overall aesthetic appeal of a ruby.


Understanding Ruby Purity: The Four Cs

Similar to diamonds, the quality and purity of rubies are assessed based on the four Cs: color, clarity, cut, and carat weight.


1. Color:

The most crucial factor in determining the value and purity of a ruby is its color. A pure ruby exhibits a vivid, deep red hue often referred to as “pigeon blood” red. This color is a result of the presence of chromium in the stone. To assess the purity of a ruby’s color, hold the stone in natural light and observe its intensity. Be cautious of stones that appear too light or have undertones of brown or orange, as these may indicate lower purity levels.


2. Clarity:

Clarity refers to the presence of inclusions or internal flaws within the ruby. While most natural rubies do have some inclusions, higher purity stones have fewer and less noticeable imperfections. A pure ruby will allow light to pass through it unobstructed. Use a jeweler’s loupe to examine the stone closely for any visible flaws, cracks, or cloudiness.

3. Cut:

The cut of a ruby impacts its brilliance and overall appearance. While there are various cuts, the most common for rubies is the cushion or oval cut. A well-cut ruby will exhibit a symmetrical shape, balanced proportions, and proper facets that enhance its luster. Irregular cuts or poorly defined facets may indicate a lower quality stone or one that has been treated.

4. Carat Weight:

The carat weight of a ruby is a measure of its size. However, size alone does not determine a ruby’s purity. It’s essential to consider carat weight in conjunction with the other three Cs to accurately assess a stone’s overall quality and authenticity.

See Also: 7 Factors That Determine the Value of a 10-Carat Ruby

Using the Ruby Purity Test: Step-by-Step Guide

To determine the purity of a ruby gemstone, follow these step-by-step methods that combine visual examination and some basic tools.

1. Visual Examination:

a. Color Assessment:

Place the ruby under natural sunlight or a white light source. Examine the color closely and compare it to a reference chart of ruby colors. A pure ruby will display a rich red color with no undertones of other colors.

b. Inclusion Inspection:

Hold the ruby up to the light and look for inclusions. Some inclusions are acceptable in natural rubies, but excessive or highly visible inclusions may indicate lower purity or a synthetic stone.

c. Surface Examination:

Check the surface of the ruby for scratches, pits, or unnatural-looking textures. Natural rubies might have minor surface imperfections, but an unusually rough or heavily flawed surface could be a sign of a lower quality stone.

2. Use of Tools:

a. Jeweler’s Loupe:

Examine the ruby with a jeweler’s loupe (a small magnifying glass). Look for internal flaws, cracks, or irregularities that might not be visible to the naked eye.

b. UV Light:

Some rubies fluoresce under ultraviolet (UV) light. Shine a UV light on the ruby and observe its reaction. A strong fluorescence could indicate the presence of treatments or synthetic materials.

3. Certification and Expert Opinion:

a. Gemological Reports:

Obtain a gemological report from a reputable gem lab. These reports provide detailed information about a ruby’s origin, treatment, and quality. A certified natural ruby will have a higher level of purity.

b. Consult a Gemologist:

If in doubt, seek the expertise of a certified gemologist. They can use advanced equipment to analyze the ruby’s properties and provide a reliable assessment of its purity.

Spotting Treated and Synthetic Rubies

In today’s market, it’s essential to be aware of treated and synthetic rubies that can mimic the appearance of natural stones. Here’s how you can identify them:

1. Treated Rubies:

a. Heat Treatment:

Heat treatment is a common practice to enhance the color and clarity of rubies. While most natural rubies undergo this process, excessive heat treatment can impact their purity. Look for signs of over-enhancement, such as an overly uniform color.

b. Filling:

Some rubies are treated with lead glass to fill surface-reaching fractures. These fractures may be visible under magnification and can indicate a treated stone.

2. Synthetic Rubies:

a. Uniform Color:

Synthetic rubies often have a remarkably consistent and uniform color due to their controlled growth process. Natural rubies may exhibit slight variations in color.

b. Lack of Inclusions:

Most synthetic rubies have fewer inclusions than natural ones. If a ruby appears flawless under magnification, it might be synthetic.

c. Flux or Flame Fusion:

Look for curved growth lines or gas bubbles, which can be indicative of synthetic rubies created through flux or flame fusion methods.

Ethical Considerations and Sourcing

In addition to assessing purity, ethical considerations surrounding ruby sourcing are of growing importance. Many rubies on the market originate from regions with complex mining practices and potential human rights issues. To ensure that you are purchasing a ruby with ethical origins, consider the following steps:

1. Ask for Documentation:

Request information about the ruby’s origin and mining practices from the seller. Reputable dealers often provide details about their sourcing efforts.

2. Support Responsible Brands:

Choose brands and jewelers that are committed to ethical sourcing and sustainable practices. Look for certifications like the Responsible Jewellery Council (RJC) certification.

3. Consider Lab-Grown Options:

Lab-grown rubies offer an alternative to mined stones and are often more environmentally friendly. They also eliminate concerns about unethical mining practices.

See Also: How to Wear a Ruby Ring in Astrology: A Step-By-Step Guide


Assessing the purity of ruby gemstones requires a combination of knowledge, observation, and sometimes, expert consultation. By understanding the four Cs of ruby quality, using visual examination techniques, employing basic tools, and being aware of treated and synthetic stones, you can make informed decisions when purchasing rubies. Additionally, keeping ethical considerations in mind ensures that your choice aligns with responsible sourcing practices. Whether you’re an avid collector or simply an admirer of these magnificent red gems, this comprehensive guide equips you with the tools to appreciate the beauty and authenticity of ruby gemstones.


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