Guide to Gems: Illustrated Guide to the Identification, Properties and Use of Gemstones
Guide to Gems: Illustrated Guide to the Identification, Properties and Use of Gemstones
Guide to Gems: Illustrated Guide to the Identification, Properties and Use of Gemstones Guide to Gems: Illustrated Guide to the Identification, Properties and Use of Gemstones

* Book Type:

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Publisher: Firefly Books

Author Statement: Cally Oldershaw
Series Name: Firefly Pocket series
Audience: Trade
Specs: 900 color photographs and illustrations, maps, glossary, useful addresses, index
Pages: 224
Trim Size: 5" x 7 3/4" x 1/2"
Language code 1: eng
Publication Date: 20090101
Copyright Year: 2003
Price: Select Below

Guide to Gems: Illustrated Guide to the Identification, Properties and Use of Gemstones

A guide to the identification, structure, and uses of precious and semi-precious stones, novelty stones, agates, and crystals.

A reference guide to gems, semi-precious stones and crystals.

Gemstones and crystals are used for jewelry, industry, lasers and precision technology. Firefly Guide to Gems is a practical, compact guide to the identification and use of precious and semi-precious stones, novelty stones, agates and crystals.

An introduction explains geology, chemistry and gemstone properties in clear and accessible terms. Key aspects of gemstones are explained such as crystal structures and optical and physical properties.

The first section of the book focuses on precious gems in their many forms, with illustrations of priceless jewelry. Practical information includes:

  • Fashioning and cutting
  • Types and shapes of cut
  • Collecting
  • Handling and storing gemstones
  • Weighing and measuring stones

The second and main section supplies complete descriptions of a wide range of gems, organized by chemical composition, for instance:

  • Carbon (diamond)
  • Aluminum oxide (saphire and ruby)
  • Phosphate (turquoise)
  • Silica (opal)

A fascinating profile of each gem is accompanied with color photographs of the raw crystal, common cuts, and finally polished for use in jewelry. At-a-glance charts provide technical details such as refractive index, crystal group, luster, hardness and cleavage for each gem.

Easy-to-read and abundantly illustrated, Firefly Guide to Gems is ideal for collectors and rockhounds.


Cally Oldershaw is a mineralogist and Liaison Officer for the Geological Society of London as well as an examiner for the Gemmological Association of Great Britain.



We often use the word 'gem' in everyday language, for example 'she is a real gem' and 'this book is a little gem'.. In this context a gem is something special, highly valued and well-thought of, something to be treasured, with special attributes.

Gemstones are also treasures -- something special. Their unique qualities have been valued throughout the ages, across continents and by different peoples, from our earliest ancestors to the present-day. It may have been the color or the crystal shape of a gemstone. or a brightly colored shell that first attracted the attention of someone who then bent down to pick it up. Something special about it would have encouraged that person to keep it, to own it, maybe to put it in a special place such as a bag hung around the neck, for safekeeping, to polish or make a hole in it, or to tie it onto clothing as an adornment or as a piece of jewelry.

Gems and jewels are associated with the rich and famous, We may admire the jewels worn by our favorite film star, celebrity, or sportsperson. We may even aspire to own some particularly fine piece ourselves. Gems have been worn as a symbol of status, adorning the crowns of royalty - a visual reminder of wealth, success and achievement to both the wearer and the observer. The mystic power and energy ascribed to certain gemstones are an attribute defined by healers. The tales of famous stones, the luck they may hold or the curse they may inflict, can captivate an audience.

In choosing this book, you may already have been captivated by the 'specialness' of gemstones, or you may be interested in knowing more about them. We hope that this book inspires and informs you. It is intended as a guide to the beautiful and fascinating world of gemstones. It shows you the glorious diversity of colors and the incredible crystal shapes of these wonders of the natural world.

Some crystals look as fragile as glass and are incredibly rare, but they have an inherent strength. Crystals may take millions of years to form, or may form as you watch. They may have been formed in rocks deep beneath the Earth's surface, or they may be survivors of mountain-building episodes or devastating volcanic eruptions, or they may have been washed into rivers and streams to be retrieved maybe millions of years after their formation. These survivors are nature's treat: perfect and brightly colored crystals formed in dark, deep rocks.

But for a gemmologist (someone who studies the science of gemstones, their physical and optical properties and their origins), what are the special attributes of gemstones? For gemstones to be used in jewelry, ideally they should have three main attributes: beauty, durability and rarity. However, not all gemstones possess all three. For example, some may be insufficiently durable (hard and tough) to use as a cut gemstone in a ring, but may be good for fashioning as a piece within a brooch, protected from damage by the mounting. Beauty and rarity have a direct impact on the value of a gemstone, the more beautiful and rare, the greater the price that will be paid.

Generally speaking, gemstones are minerals that have formed as sufficiently clear, large crystals that can be cut and polished for use as pieces for personal adornment or objects d'art such as sculptures, inlays etc. Precut gemstones and minerals in matrix are also collectable. In addition to the mineral gemstones there are also other materials that can be used for adornment, such as PEARL, SHELL, AMBER and other derivatives of plants or animals. These are called organic gems.

But not all gemstones are what they seem. A gemstone that has similar properties to a more valuable or rare specimen may be used to imitate it. Color can be misleading: for example, at first glance the color of a red SPINEL might be mistaken for a RUBY. Glass, plastic and other materials both natural and man-made can also be used to imitate gemstones.

Even the assumption that a gemstone has been formed naturally in the rocks of the Earth, may not be true. Synthetic gemstones have the same chemical and physical properties as their natural equivalent, but they are made in the laboratory. Part of the excitement of being a gemmologist is to know how to use your eyes and the various pieces of equipment available in order to distinguish the imitations, fakes and forgeries from the real gems.




Gem formation
Crystal structure
Optical properties
Physical properties
Fashioning and cutting
Imitation and synthetic stones
History of gems
Famous diamonds

Color key



Carbon (diamond)
Oxides and hydroxides
Sulfates and chromates
Igneous rock
Synthetics and imitations
Precious metals

Maps of gem locations


Useful address and acknowledgments


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