If it’s an upper case “L” in addition to a decrease case “c”, it’s for Louis C Marks who built jewelry in the 40s. SETA is a firm that provides fashion jewellery. Their jewellery normally features a CZ plating over silver. CN signifies that the jewellery is produced in China, https://griffinugqbm.madmouseblog.com/17545134/the-ultimate-guide-to-jp88