Swedish Blue Stone (or Bergslaggsten) wrapped in Rose Gold-filled and Argentium Silver wire. It includes a Rose GF chain. 
This isn't actually a stone, but rather a polished piece of slag from medieval iron forges found in Bergslagen (mining district), Sweden. The blue color was formed from metal ores containing copper. The slag pile that this came from had been grown over and covered by vegetation since the Middle Ages. It was discovered centuries later by a Swedish goldsmith. The striking shade of blue reminds me of the blue in the Swedish flag.