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					Originally Posted by  Marius66
					 
				 
				There is a deep black side and a ''brighter''-""metallic'' on the sharp edge side of the blade without guard. 
Is that what you call a '' heat quenched edge'' ? 
 
Kind regards 
			
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 It could be. Your latest pictures seem to show differential hardening but etching would likely bring it out better. Heat and then quenching with oil or water will create a different crystalline structure and harder edge, which shows as a line along the edge that is a different color from the rest of the blade.