CREATE TABLE table_7700 ("Material" CLOB, "Formula" CLOB, "Refractive index ( es )  589.3nm" CLOB, "Hardness  (  Mohs' scale  ) " CLOB, "Density  ( g/cm 3  ) " CLOB, "State of the art" CLOB)

Which material has a hardness of 8.25?
SELECT "Material" FROM table_7700 WHERE "Hardness ( Mohs' scale )" = '8.25'
SELECT "Material" FROM "table_7700" WHERE "Hardness ( Mohs' scale )" = '8.25'