Rubies from Mong Hsu

Peretti, Adolf; Schmetzer, Karl; Bernhardt, Heinz-Jürgen; Mouawad, Fred

doi:10.5741/gems.31.1.2

Cited by 49 publications

(44 citation statements)

References 29 publications

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“…we studied about 50 crystals with a Schneider horizontal (immersion) microscopel which had a specially designed sample holder as well as specially designed (to measure angles) eyepieces (Schmetzer! 1986;Kiefert and Schmetzer) 1991; see also Peretti et al! 1995).…”

Section: Methodsmentioning

confidence: 99%

Russian Flux-Grown Synthetic Alexandrite

Schmetzer¹,

Peretti²,

Medenbach³

et al. 1996

Gems & Gemology

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Synthetic alexandrite is being fluxgrown in Rz~ssia in a molybdenum-, bismuth-, and germanium-bearing solvent by means o{ the reverse-temperature gradient method. Characteristic properties include habit, twinning, growth patterns, residzial flux inclusions, trace-element contents, chemical zoning, color zoning, and spectroscopic feat~zres in the visible and infrared ranges. The relationship between production technique and characteristic properties is discussed, and diagnostic properties that can be used to distinguish these synthetics from natural alexandrite are disclosed.h e alexandrites are even rarer than fine rubies! sapphires, and emeralds. The major factors determining (F price are size! clarity! brilliancy! color in daylightl color change in artificial light! and country of origin. The finest alexandrites are characterized by a lively and intense green color in daylight with a prominent color change to purplish red or redhsh purple in incandescent l&t. The most prestigious source of natural alexandrites is Russia! specifically the Ural mountains, where they were first discovered. Fine alexandrites occasionally appear at international auctions. For example! a 31 ct alexandrite sold for almost US$185,000 at Christie's May 1992 auction in Geneva. Dealers in IdarOberstein report the sale of fine! large (over 5 ct) alexandrites for $101000-$201000 per carat, and even higher for exceptional stones (R. Guerlitz and A. Wild! pers. comm.r 1996).During the past 10 years! new deposits of natural alexandrite have been found in Minas Gerais! Brazil (Banlz et al.! 1987; Proctorl 1988; Cassedanne and Roditi, 1993; Karfunlzel and Wegner! 1993); in Orissa and Madhya Pradesh! India [Patnailz and Nayalzl 1993;Newlay and Pashine! 1993); and! most recently! near Songea in southern Tanzania (see ''News on the Songea Deposit . . . Kammerling et al.! 1995).In addition! gem alexandrites are still being recovered from the historic emerald deposits of the Ural Mountains (Eliezri and Kremlzowl 1994; Laslzovenlzov and Zhernalzovl 1995).As greater quantities of gem alexandrite enter the marlzet! significant amounts of faceted alexandrites are being submitted to gemological laboratories for testing. occasion ally^ distinguishing natural from synthetic has been difficult! notably for flux-grown syntheticsl but especially when a specimen lacks diagnostic mineral incl~~sions (see Banlz et al.! 1988; H e m and Banlzl 1992; Kammerhg, 1995). These difficulties are caused by the similarity of growth structures and healing "feathers" in natural alexandrites from different localities to residual flux feathers in fluxgrown synthetic alexandrites. In addition! hematite platelets in natural alexandrites sometimes resemble platinum inclusions in their flux-grown synthetic counterparts. Synthetic Alexandite GEMS & GEMOLOGY Fall 1996The Russian-produced synthetic alexandrites (figure 1) can imitate the highest-quality nat~lral alexandrites-such as those from the Ural mountains. Yet some natural alexandrites have sold for up to 300 times as much ...

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Section: Methodsmentioning

confidence: 99%

Russian Flux-Grown Synthetic Alexandrite

Schmetzer¹,

Peretti²,

Medenbach³

et al. 1996

Gems & Gemology

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“…This filling did improve the stones' face-up appearance and could add weight, but it could also readily be detected with magnification. The early 1990s witnessed the marketing of huge quantities of ruby from Mong Hsu, Myanmar, with multiple cavities and fractures that were filled with, or partially healed by, glassy substances added during high-temperature heat treatment (Peretti et al, 1995;McClure and Smith, 2000). The term residue began to be applied to this kind of material, in reference to the glass that was a side effect of the real intent, which was to heal the fractures.…”

Section: G Identification and Durability Of Lead Glass-filled Rubies mentioning

confidence: 99%

Identification and Durability of Lead Glass-Filled Rubies

McClure¹,

Smith²,

Wang³

et al. 2006

Gems & Gemology

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In early 2004, the GAAJ laboratory in Japan issued a lab alert about rubies they had seen that had large numbers of fractures filled with high-lead-content glass, which made them appear very transparent. Since then, large quantities of this material have reached international markets. This dramatic treatment is not difficult to identify with a standard gemological microscope, since it has characteristics similar to clarity-enhanced diamonds (flash effect, gas bubbles, etc.). However, locating filled cavities in reflected light is more challenging, as the surface luster of the filler is close to that of ruby. The filling material appears to be very effective in reducing the appearance of fractures. Durability testing of a few samples by highly skilled jewelers indicated that the filler was fairly resistant to heat exposure during jewelry repair procedures, but it reacted readily with solvents.

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“…The disclosure that such substances were present in fractures and surface depressions caused a great deal of controversy in the industry, which contributed to the significant drop in price of heat-treated rubies in the latter half of the decade (see, e.g., Peretti et al, 1995;Shigley et al, 2000a). Many in the industry felt that this material was only a by-product of the heating process (Robinson, 1995), while others felt that it was put there intentionally (Emmett, 1999).…”

Section: Ruby and Sapphirementioning

confidence: 99%

“…This debate was fueled primarily by the discovery of large quantities of ruby near the town of Mong Hsu in the upper Shan State of Myanmar (formerly Burma). Virtually all of this material had to be heated to improve its quality, either by removing the blue "cores" that typically occur down the center of the crystals or by filling or partially healing the many fractures (see, e.g., Peretti et al, 1995). The fluxes used during the heat-treatment process melt, flow into surface-reaching fractures and cavities, and subsequently re-solidify on cooling as an amorphous, vitreous solid (i.e., a glass).…”

Section: Ruby and Sapphirementioning

confidence: 99%