Gem Knowledge: What Are the ‘Cardinal Gems’? 

If you’ve ever heard the phrase ‘cardinal gems’ and wondered what this means, now’s your chance to find out. Gem-A Gemmology Tutor Pat Daly breaks down this historic term and explains how the concept has stood the test of time. The term ‘cardinal gems’ may be used to spotlight five stones – diamond, ruby, sapphire, […]

Fluorescence in Diamonds

Diamonds are the best known and are among the most popular stones in the jewellery trade, having been valued for more than 2,000 years. If you have heard about diamonds fluorescing under ultraviolet light but don’t quite know what this means, how it’s relevant to gemmologists, or why it matters to diamond collectors, Pat Daly FGA DGA is here […]

Gem Knowledge: Understanding Spectroscopy in Gemmology

Spectroscopy is the observation or measurement of the absorption and emission of electromagnetic radiation by gemstones. Today, this methodology and its associated tools are vital for gemmologists and can be used to reliably indicate a gemstone’s identity. Here, Gem-A Gemmology Tutor Pat Daly explains more about the history and significance of this scientific technique.   Sir Isaac Newton observed the spectrum of […]

Gemmology Insights: What Are the Rarest Colours in Gemstones?

Colour is one of the most appealing features of gemstones and is often the main reason why they are valued. However, it is also true to say that some mineral colours are rarer and more prized than others. Here, Gem-A Gemmology Tutor Pat Daly explores the nuanced world of colour in gemstones, including brilliant reds, Kashmir sapphires, […]

Beginner’s Guide: The 8 Most Popular Diamond Cuts and Faceting Styles

When we look at faceted gemstones, we see and appreciate their colours, transparency, brilliance and fire. What we sometimes take for granted, however, is the fashioning that makes it possible to enjoy these visual effects. To explain more, Gem-A Gemmology Tutor Pat Daly has created this useful introduction to diamond cut and shape, incorporating faceting […]

Gemmology Insights: How To Recognise Dyed Gemstones and What to Look Out For

Dyeing is probably the most common and cheapest way to treat gem materials, to make inferior stones seem to be of good quality or to substitute inexpensive materials for costly natural stones. Here, Gem-A Gemmology Tutor Pat Daly takes a closer look at dyed material and explains how experienced gemmologists can identify evidence of such […]

Gem Knowledge: What is Artificial Glass Paste in Antique Jewellery

Gemmologists often encounter simulants of natural gemstones, like artificial glass paste. Synthetic and composite stones of various kinds may be troublesome to identify, but those made of glass are among the most common and are usually easy to recognise. As Gem-A Tutor Pat Daly describes in the article below, glasses may also be natural stones, […]

Gemmology Insights: Once in a Lifetime Inclusions for Gemmologists

The fascinating internal world of gemstones is an important area of study for gemmologists. Although some inclusions are common, others are far rarer and more elusive. Some professionals may go their entire lives without seeing these specific internal features in person. Here, Gem-A Tutor Pat Daly shares some ‘once in a lifetime’ inclusions and what […]

Gemmology Insights: Why is Peridot Described as Oily?

The description ‘oily green’ is sometimes used in connection with peridot. It is not intended as a criticism; it is a term which has been traditionally associated with the colour of this stone. Here, Gem-A Tutor Pat Daly explains why this descriptive moniker is used and what it tells us about this vibrant green mineral… Peridot is a beautiful gemstone It can be brown […]

Understanding Spinel: A Gemstone with Brilliance and Vibrancy

If you are new to gemmology, you may not be wholly familiar with the gem material known as spinel. Historically, these gems were confused with corundum, especially in red hues, which adds to its mystery and intrigue for gemmologists. Today, however, they are an important stone used in fine and high jewellery and deserve their own spotlight. Here, Gem-A tutor Pat Daly […]