Italian submarine Gemma was a built for the Royal Italian Navy (Regia Marina) during the 1930s. Her name in Italian means a gemstone or jewel. Design and description The Perla-class submarines were essentially repeats of the preceding . The modifications that were made compared to the boats of the previous series were mostly of upgrade nature. Among them were enlargement of the false tower at the top, more modern engines, installation of a radiogoniometer that could be controlled from inside the ship. Improvements and the installation of new air conditioning equipment meant a slight increase in displacement, and increase in the fuel stowage also increased the autonomy of these boats compared to the previous series. Their designed full load displacement was surfaced and submerged, but varied somewhat depending on the boat and the builder. The submarines were long, had a beam of and a draft of to . For surface running, the boats were powered by two diesel engines, each driving one propeller shaft with overall power of . When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Perla class had a range of at , submerged, they had a range of at . The boats were armed with six internal torpedo tubes, four in the bow and two in the stern. One reload torpedo was carried for each tube, for a total of twelve. They were also armed with one deck gun for combat on the surface. The light anti-aircraft armament consisted of one or two pairs of machine guns. Construction and career Gemma was built by CRDA at their shipyard in Monfalcone, laid on 7 September 1935, launched on 21 May 1936 and completed on 8 July 1936. After delivery, Gemma was assigned to the 35th Squadron (III Submarine group) based at Messina. After a brief training, she carried out a long endurance cruise in the Dodecanese in the fall of 1936. She repeated the same endurance cruise in the Dodecanese in 1937. From August 27 through September 5, 1937 Gemma, under command of captain Carlo Ferracuti, carried out a secret mission in the Strait of Sicily during the Spanish Civil War. She made three attempts to attack during this mission, but no actual attacks happened due to impossibility to identify the targets with certainty. Upon completion she returned to Augusta. In 1938, Gemma together