Abstract
1) From in-situ observation and analysis of Congo diamond, it contains nano-particles of carbonates (including calcite) and gypsum, together with halite of clear crystal plane and grains of Fe-silicates(without Mg) covered wholly by irregular carbon-bearing grains.
2) Kimberley diamond of South Africa shows different grains of Ca,Mg,Fe and Ti -bearing carbonates (without halite in composition).
3) From other data of diamond texture, Congo diamond is considered to be formed at shallow place by discarding previous history.
