Figure 11. This diagram illustrates the kinds of secondary diamond deposits found along the Santo Inácio River in Minas Gerais—alluvial and colluvial deposits along the river channel, occasional kimberlite pipes (often unrecognized because they are deeply weathered and covered by younger sediments), and sedimentary conglomerates exposed on the adjacent hillsides.
Figure 10. A map showing the distribution of various categories of diamonds found in Brazil. The name of the mining area is shown (with the abbreviation of the Brazilian state), preceded by its location number on the map.
Figure 9. A simplified map of the major geological regions of Brazil.
Figure 8. Crystals such as this group from the Jequitinhonha River were once used as markers in card games, as they were not recognized as diamonds. Photo by Robert Weldon/GIA, courtesy of Gar Mineração.
Figure A-2. The most common outlines for “brilliant cut” diamonds, as illustrated in A Treatise on Diamonds and Pearls by David Jeffries in 1750. Note that all have 58 facets in a similar layout, and the only differences are their outlines.
Figure 7. This star motif necklace with “Old Mine” cut Brazilian diamonds was made in 1865. Photo by Luisa Oliveira, courtesy of Ajuda National Palace.
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