Sapphires from Southern Vietnam

Sapphires from Antsiranana Province, Northern Madagascar

“…This unusual feature is rarely found elsewhere. Similar colorless core zones, but with a triangular outline, occur in blue magmatictype sapphires from Vietnam (Smith et al, 1995).…”

“…In particular, these sapphires formed as barrel-shaped crystals with dominant w or z hexagonal dipyramids, and subordinate c, r, and n faces; prismatic forms were not observed. The correlation between external crystal faces and internal growth structures has been shown for corundums from practically all basalthosted sources (Kiefert, 1987;Kiefert andSchmetzer, 1987 and1991), including magmatic Vietnamese sapphires (Smith et al, 1995).…”

“…The absorption spectra of the Ambondromifehy sapphires (see, e.g., figure 23) are typical of those recorded in BGY magmatic sapphires from other localities (see, e.g., Bank, 1980, 1981;Schmetzer, 1987;Kiefert and Schmetzer, 1987;Smith et al, 1995). We recorded a continuous series of absorption spectra covering the entire range of colors, including yellow, greenish blue, and intense blue to blue-violet (figure 24A-C).…”

OH in naturally occurring corundum

“…Such concerns are justified in view of the observations of Smith (1995) and Peretti et al (1995) of comparable sharp OH bands in heat treated ruby, but not in untreated natural samples. Further confirmation of OH in natural corundum is presented by Smith et al (1995) who stated that OH bands are observed in the IR spectra of blue sapphires from basaltic sources in southern Vietnam, and Emmett et al (2003) who reported OH bands at 3367, 3310, 3233, and 3185 cm -1 in a pink sapphire from Vietnam. The present study represents an extension of the initial examination of natural corundums with many samples with better controlled histories.…”

Rubi e safiras de Minas Gerais, Brasil

“…Os espectros referentes às amostras de Indaiá são muito semelhantes aos obtidos em Palmeiras e Sapucaia, mostrando uma banda de absorção entre 370 e 420nm, que, em safiras azuis do Sri Lanka, Mianmar, Vietnam e outras (Smith et al, 1995), é associada à presença de Fe 3+ . A faixa entre 500 e 600nm, região indicativa do mecanismo Fe 2+ -Ti 4+ e da presença de Cr 3+ , apresenta-se na forma de bandas largas e suaves (Figura 6).…”