IEC 60758:2008(E) applies to synthetic quartz single crystals intended for manufacturing piezoelectric elements for frequency control and selection. This fourth edition cancels and replaces the third edition, published in 2004. This edition constitutes a technical revision. It includes the following significant technical changes with respect to the previous edition: preparation of AT-cut slice sample for etching is changed to make it easier; etch channel grade classification is changed considering request of the user and explanation of quartz axes difference between IEEE and IEC is added as Annex F.