Late formation of additional diamond layers on top of the graphites would have converted them to covered internal features within the larger diamond (R.H. Hodkiewitcz, “Characterizing graphene with Raman spectroscopy,” Application Note: 51946, Thermo Fisher Scientific, Madison, Wisconsin, 2010). This also explains the shift of the G band to a higher energy, due to the higher strain near these newly formed secondary graphite crystals (J. Since this G band is at a slightly higher energy level than that from the primary graphite, which usually peaks at around 1580 cm –1, we propose that the crystals tested are likely the secondary graphite converted from part of the original diamond into graphite form during the specific growth episode when oxidized fluids rich in CO 2 and H 2O passed through diamond bearing horizons. Jang, Ed., New Developments in Photon and Materials Research, Nova Science Publications, 2013). Childres et al., “Raman spectroscopy of graphene and related materials,” in J.I. Photo by Yixin (Jessie) Zhou field of view 7.19 mm.įurther analysis using Raman spectroscopy reveals that the dark inclusions are graphite crystals with a Raman peak at 1590 cm –1 (figure 3), which corresponds to the graphite G band (I. Minute graphite inclusions outline the octahedral crystal faces in this diamond. Advanced gemological analysis with UV-Vis and FTIR spectroscopy confirmed that this was a natural diamond with a natural color origin.įigure 2. Gemological examination at 60× magnification reveals that the octahedral-shaped inclusion is outlined by numerous irregular dark crystals (figure 2). GIA’s New York laboratory recently received a 1.30 ct Fancy brownish greenish yellow diamond (figure 1) containing an octahedral-shaped inclusion outlined by minute crystal inclusions along the junctions of the crystal faces. Snelling, “Diamonds – Evidence of explosive geological processes,” Creation, Vol. During the ascent to the earth’s surface, diamonds may be converted, partially or entirely, to graphite and chemically dispersed and eliminated (A.A. Primary diamond deposits are usually found in mantle-derived igneous rocks, with the principal hosts being kimberlite and lamproite. This 1.30 ct Fancy brownish greenish yellow diamond contains an octahedral-shaped inclusion.
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