From Crystal Growth Technology

Shuji Oishi
Department of Environmental Science and Technology, Faculty of Engineering, Shinshu University, Wakasato, Nagano 380 8553, Japan

17.1 Introduction

Gemstones are usually used for human ornamentation. Diamond (C), ruby (Al 2O 3:Cr), and emerald (Be 3Al 2Si 6O 18:Cr) are well-known gemstones. The gemstones are principally natural minerals that are highly valued for their beauty, durability, and rarity. Portability is also required for the use of gem materials. The majority of gemstones are single crystals of minerals. As an example of natural minerals, spessartine garnet crystals found at Wada-toge Pass, Nagano Prefecture, Japan, are shown in Fig. 17.1. The garnet crystals have a beautiful glassy luster, and are black and opaque. They can be used for ornamental purposes without cutting. Other gemstones are not single crystals. Opal is one of the best-known non-crystalline gemstones. Natural minerals of good quality are getting scarce with the passing of time.

Figure 17.1: Natural garnet crystals found at Wada-toge Pass, Nagano Prefecture, Japan

The high value placed on gemstones for use in jewelry has led to many attempts to synthesize natural gemstones. The duplication of beautiful gemstones in the laboratory has been one of man's aims. Manmade and natural gemstones have the same chemical composition and crystal structure. Ruby crystals were grown by the flux method in 1837 by Gaudin [1]. He grew ruby crystals of up to 0.187 g from molten potassium alum and potassium chromate. Small emerald crystals were grown from lithium molybdate and lithium vanadate...

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Sapphire Materials and Components
Sapphire materials and sapphire components consist of a single-crystal or monocrystalline form of aluminum oxide (Al2O3). As ceramic materials, they have superior hardness, mechanical and optical properties. Applications include jewel bearings, lasing rods, wear parts, wafer substrates and optics.
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Garnet, emery and mineral abrasives include mined grains such as pumice, carborundum, natural diamond, tripoli, rouge, staurolite, novaculite, silica and other silicate minerals.
Crystallizers are forced-circulation evaporators.

Topics of Interest

David C. Smith 21.1 Introduction to the Historical Development of Raman Microspectroscopic Work on Crystals, Rocks and Gemstones 21.1.1 The Advent of Raman Microspectroscopy and its Consequences...

Lore Kiefert Jean-Pierre Chalain1 Sabine H berli2 22.1 General Introduction During the past few decades, Raman spectrometers have gradually become a standard tool for major gemmological laboratories,...

Krishan Lal, R.V. Anantha Murthy, Ashutosh Choubey, and Niranjana Goswami Crystal Growth and Characterization Section, National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi-110012, India...

1.5 EMERALD LASERS The lasing of trivalent chromium ions in an emerald crystal at the electronic-vibrational transitions 4 T 2 ? 4 A 2 was examined for the first time in Ref. 35. The adjustable...

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