(IDEX Online) - Signet Jewelers rose up the rankings in the National Retail Federation (NRF) new list of Top 100 Retailers in the US - from 98th place to 78th.But its total retail sales plunged by almost a quarter from $6.05bn in 2019, to $4.65m in 2020 according to the NRF data, provided by Kantar data analytics. Walmart and Amazon.com, placed first and second respectively in both 2020 and 2021, also saw sales down significantly.Signet is the biggest retail jeweler in the US, the world's biggest diamond retailer, and parent company of Kay Jewelers, Zales, Jared, H. Samuel, Ernest Jones, Peoples, Piercing Pagoda, Rocksbox and JamesAllen.com.It had 2,381 U.S. stores in 2020, a drop of nine per cent compared with 2019. The company has been moving out of poor-performing malls and investing heavily on its online activities.