Bitcoins are widely called “digital gold,” so it's fitting that many crypto fans like their physical gold, too. Several companies have sprung up in the last two years to serve this bitcoins-to-gold market. Why buy gold? Some choose it as a savings instrument, others a trading commodity, and still others as a fiat-free hedge against crypto volatility. Whatever your purpose, the following five companies may pop up onto your radar: Serica This San Francisco-based company was rebranded this year from the name DigitalTangible. They've been called a “trailblazer in the gold-bitcoin space” for launching the first online gold/bitcoin trading platform …