Question: What hardness has a formula of Y 3 Al 5 O 12?
SQL: SELECT "Hardness ( Mohs' scale )" FROM "2-1608081-1" WHERE "Formula" = 'Y 3 Al 5 O 12';

Question: Which formula has a refractive index 589.3 at 1.97?
SQL: SELECT "Formula" FROM "2-1608081-1" WHERE "Refractive index(es) 589.3nm" = '1.97';

Question: How much is the density with a hardness of ~ 8.3?
SQL: SELECT "Density (g/cm 3 )" FROM "2-1608081-1" WHERE "Hardness ( Mohs' scale )" = '~ 8.3';

Question: Which material has a hardness of 8.25?
SQL: SELECT "Material" FROM "2-1608081-1" WHERE "Hardness ( Mohs' scale )" = '8.25';