What did the Gestapo wear?

Answer 1

Normally, the Gestapo wore civilian clothing. In occupied territories, they sometimes wore field-grey SS uniform. The right collar patch was a plain black trapezium (they never wore the SS-rune insignia! That was reserved for German Waffen-SS regiments). The left collar patch indicated their SS-equivalent rank. They wore police-style shoulder straps that also indicated their rank. They wore the SD insignia on their lower left arm.

Answer 2

The Gestapo wore plain and formal clothes to blend in since they were the 'secret force' and worked Behind the Scenes. Although some wore the classic gray military ware and some had the letter 'SS' stitched onto their collars.

Additional Answer

As the above answer points out, members of the Gestapo normally wore civilian clothing when operating in civilian areas. However, when called to operate in combat areas (e.g. in the Soviet Union), they were accorded the protection of wearing uniforms. These uniforms were the same as those of the Waffen-SS (field grey -a grey/green colour), except that their badges would indicate their membership of a police formation. However, they would notwear the SS-runes (double-lightning flash) on their right-hand collar patch which, instead, would be plain black, as the SS-runes were strictly reserved for German members of the Waffen-SS (combat formations of the SS), and no other SS organisation. Their SS-equivalent rank would be indicated on their left-hand collar patch, and their shoulder straps (also used to indicate rank) would be police, rather than military, pattern. Those Gestapo members qualified to do so would also wear the letters 'SD' (standing for 'Sicherheitsdiest' -the security service of the SS) embroidered on a trapezium, outlined in metallic thread, worn on their left cuff.