"Anneal, to treat a metal at a more or less high temperature, in order to eliminate the effects of quenching or hammer-hardening. Annealing is usually done in an oven, away from the air, to avoid oxidation and decarburization, and the metal is allowed to cool slowly." (Berner)
Blueing, is a term used to describe the process where hardened polished steel is heated until the polished surface oxidises and becomes blue, (being blued).
Harden, conventionally used term to describe increasing the hardness of steel through quenching heated carbon steel either in oil or water.
Hardness, "The degree of hardness of a metal can measured using different techniques. By impression: a hard object (a ball of hardened steel or a diamond cone or pyramid) is pressed with a given force and for a certain time upon the substance that is to be tested. The dimensions of the impression enable the hardness to be calculated (Brinell, Rockwell, Vickers or Knoop scale of hardness). By rebound: a hard object is dropped from a known height upon the material to be tested for hardness. The height of its rebound indicates the hardness (Shore's scleroscope).
By scratching: hardness is measured by the scratching-power of various graded materials used as standards of different degrees of hardness (Mohs scale)." (Berner)
Sclerometer, "Apparatus used for measuring the hardness of metals. The metal is scratched by a diamond point, under known pressure; the width of the scratch depends on the hardness of the metal. The Martens sclerometer." (Berner)
Temper, "Effect of the act of tempering. The temper of steel is indicated by the tempering-colour. These colours are due to oxidation and correspond to the following temperatures:" (Berner)
Straw-yellow 220-230°,
Golden yellow 230-240°,
Reddish brown 240-270°,
Purple 270-290°,
Dark blue 290-300°,
Light blue 300-330°,
Light green 330-400°.