This is the transitional Omega Constellation watch. Omega ended their 500 series caliber and introduced the 550 series caliber into the market. The case design remains quite similar to all 50's Constellation model. This model was introduced in 1959 and lasted to early 1961. A very interesting factory original finished bubblely aged dial. The original case is made of solid stainless steel with a solid gold case back medallion. Unpolished case. Case model is 14381 - 6 SC and measures 34.7mm across excluding the crown by 43.8mm lug tip to lug tip. Original signed crown. Brand new crystal and new case back gasket. The automatic movement is an Omega caliber 551 with 24 jewels. Movement serial is 17018418 dating this watch to 1959. It has been professionally serviced and ready for everyday wearing. Comes complete with a matching 18mm high quality handmade genuine leather strap. Wrist size in photo is 6 inches.