Distinct Ruby Suite at Sardapur, Orissa: A Spectroscopic Investigation

Abstract

Orissa is an important area for gem variety of corundum deposits in India. Spectroscopic studies, such as ESR, OAS on samples from Sardapur, Orissa, were carried out to ascertain the colour cause of corundum. Electron spin resonance (ESR) spectroscopic study was carried out on the samples to detect the presence of paramagnetic ions i.e. Fe2+, Fe3+, Ti4+, Cr3+ and V3+ etc. The variable temperature experiment carried out to observe the effect of heating on peak valence state change in paramagnetic ions. Samples were cut and polished to obtain the optical absorption spectrum (OAS) to detect the colour causing transition ions/defect centres. The samples of gem variety were step heated up to 300°C for colour enhancement studies. EPMA analysis has revealed the low chromium concentration in the rubies. The varying hues of red in the corundum are due to the presence of bivalent and trivalent iron and charge transfer process along with Cr3+ absorption in the 550 nm region.

Spectroscopic and Microstructural Studies of Ruby Gemstones of Sinapalli, Odisha

“…Of these bands at 401 nm (3.09 eV) and 535 nm (2.32 eV) are due to the spin allowed transition from the ground state 4 A 2g → 4 T 1g and 4 A 2g → 4 T 2g respectively. Such similar absorption bands due to both Cr and Fe have been reported for different ruby variety corundum samples by different authors (Cartier 2009;Majumdar and Mathew 2012). Figure 2a shows absorption spectra of the same sample before and after heat treatment.…”

“…This is the oldest mining region leading to findings of remains of Stone age and Bronze age. Ruby is also found in countries like Thailand, Vietnam, Sri Lanka, Russia, Greenland, Kenya, Tanzania, Pakistan, Afghanistan and some places in Odisha and Kashmir region in India (Atkinson and Kothavala, 1983;Majumdar and Mathew, 2012;Shor and Weldon, 2009). Corundum variety of gemstone show different colours.…”

“…Characterisation of corundum variety of ruby gemstone from different parts of the world such as Burma, Thailand, Sri Lanka, Switzerland, UK and some parts of India have been reported (Tang et al 1988;Thirangoon, 2009;Majumdar and Mathew, 2012). In this work an attempt has been made to fully characterise the gemstone samples from Sinapalli, Odisha using spectroscopy such as UV-Visible, Photoluminescence, FTIR and Raman spectroscopy.…”

Chemical and Spectral Variations between Untreated and Heat-Treated Rubies from Mozambique and Madagascar

“…Therefore, the absorption peak shifts to the purple area, the blue-purple tone of the ruby decreases, and the red hue increases, which is the main reason for the formation of the absorption band and the absorption peak moving to 385 nm and 388 nm, respectively. Such similar absorption bands due to both Cr and Fe have been reported for different rubies by previous research [20,25,37]. It has been observed that there is a decrease in the intensity of the band after heat treatment.…”

Characterisation of Eluvial Corundum (Ruby) from Kermunda, Kalahandi District, Odisha, India

“…At Jhillingdara, Mishra and Mohanty [2] reported occurrences of ruby and corundum mineralization at the contact between metapyroxenite and granite gneiss and also eluvial placer ruby in the surrounding soil horizons. Mazumder and Mathiew [3] reported corundum (ruby) crystallization in the brecciated pegmatite at contact zones of granite gneiss of Bastar craton near Sardapur area.…”