Purple to Purplish Red Chromium-Bearing Taaffeites

Schmetzer, Karl; Kiefert, Lore; Bernhardt, Heinz-Jürgen

doi:10.5741/gems.36.1.50

Cited by 10 publications

(24 citation statements)

References 18 publications

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“…In some of the taaffeites we were able to identify rounded apatite grains or magnesite crystals. These closely resemble the internal features seen in taaffeites from Sri Lanka (see, for example, Schmetzer et al, 2000Schmetzer et al, , 2005aSchmetzer et al, ,b, 2006.…”

Section: Microscopic Observationssupporting

confidence: 74%

“…The spectrum of the intense purple chromiumbearing stone shows a distinct absorption maximum at 557 nm which is assigned to an overlap of the iron-related absorption band at 557 nm with a chromium absorption located in the same spectral range (Figure 10, sample B). Chromium-bearing taaffeites from Sri Lanka with a similar absorption maximum at about 550 nm due to chromium have already been described by Schmetzer et al (2000Schmetzer et al ( , 2006.…”

Section: Spectroscopic Properties and Cause Of Coloursupporting

confidence: 70%

“…SGs and RIs of taaffeites and musgravites from Africa are compared with their individual sums of transition metal contents (V 2 O 3 + Cr 2 O 3 + TiO 2 + FeO + ZnO + MnO) in Figures 9a and b. In addition to iron, there is a strong correlation between higher zinc contents and increase in RI and SG of both species (Schmetzer et al, 2000(Schmetzer et al, , 2006Schmetzer 2005).…”

Section: Chemical Compositionmentioning

confidence: 99%

“…In contrast to the detailed knowledge of the gemmological, physical and chemical properties of gem-quality taaffeites and musgravites from Sri Lanka established so far (see references cited above), only one chemical analysis of a gem taaffeite from Myanmar is known to the authors (Schmetzer et al, 2000), and quantitative chemical data of material from Tanzania are unknown.…”

Section: Introductionmentioning

confidence: 99%

“…Although the chemical formulae for the two Be-Mg-Al-oxides, taaffeite and musgravite, are no longer in dispute, the special physical and chemical properties of chromium-, iron-and zinc-bearing, gem-quality taaffeites from Sri Lanka have come to light only within the last decade revealing more detailed knowledge of these gem materials (Schmetzer et al, 2000(Schmetzer et al, , 2005. The first quantitative chemical analyses of gem-quality musgravites from Sri Lanka were also reported recently (Schmetzer et al, 2005 c,d).…”

Section: Introductionmentioning

confidence: 99%

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A description of pearl farming with Pinctada maxima in South East Asia

Hänni¹

2007

Journ of Gemm

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This reports on a modern pearl farm in South East Asia which uses Pinctada maxima oysters. Marine biologists and geneticists supervise the pearling process. Culturing oysters from fertilized eggs has generally replaced wild oyster collection. In hatcheries larvae and spat are reared under scientifically controlled conditions. After around two years the oysters are about 12 cm in size and ready for the operation. Careful selection of donor oysters for the tissue graft and of host oysters to grow the pearls ensures optimum conditions for pearl formation. Excellent environmental conditions are sought to grow pearls of superior quality. High standards of working hygiene, X-ray checks and regular and frequent cleaning of the oysters and the holding nets are further steps to ensure high quality. Almost four years from the hatching of the larvae, the oysters are ready for a first pearl harvest. Most of the oysters are not re-beaded, and their muscle flesh is processed as seafood and the shells utilized for their nacre. The pearls are graded for quality and marketed mainly in Australia.

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Section: Microscopic Observationssupporting

confidence: 74%

Section: Spectroscopic Properties and Cause Of Coloursupporting

confidence: 70%

Section: Chemical Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A description of pearl farming with Pinctada maxima in South East Asia

Hänni¹

2007

Journ of Gemm

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Spectroscopic study of the coloured gems in a 19th century pendant from Einsiedeln Abbey

Karampelas¹,

Wörle²

2021

J Raman Spectroscopy

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Nineteen green-coloured gems adorning a cross-shaped pendant from the end of 19th century, belonging to Einsiedeln Abbey (Switzerland), were examined using non-destructive methods. Estimated weights of the gems are ranging from about 0.19 to 2.34 carats. Natural multiphase inclusions with jagged outlines were observed in all samples under optical microscope. Raman bands characteristic of beryl were observed in all samples with a 532-nm laser excitation. Raman spectra of the samples with a 785-nm laser at higher wavenumber found to be similar to emeralds containing low concentration of alkali elements. Their ultraviolet-visible-near-infrared (UV-Vis-NIR) spectra display absorption bands related to chromium and vanadium; no absorption bands related to iron were observed. Using a combination of spectroscopic and microscopic methods, the samples were adequately identified as natural emeralds, with Colombia as their most probable source.

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Efficient identification and distinction of musgravite and taaffeite with the utilization of ATR-FTIR spectroscopy and Raman spectroscopy

Thongnopkun

2024

Vibrational Spectroscopy

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Purple to Purplish Red Chromium-Bearing Taaffeites

Cited by 10 publications

References 18 publications

A description of pearl farming with Pinctada maxima in South East Asia

A description of pearl farming with Pinctada maxima in South East Asia

Spectroscopic study of the coloured gems in a 19th century pendant from Einsiedeln Abbey

Efficient identification and distinction of musgravite and taaffeite with the utilization of ATR-FTIR spectroscopy and Raman spectroscopy

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