Patents Assigned to Ludwig Muller S.A.
  • Coloring a gold alloy
    Patent number: 5164026
    Abstract: A gold alloy comprises at least gold, iron and nickel, the gold being present in an amount between about 74.4 and 94.5 percent by weight of the alloy, the iron being present in an amount between about 5.0 and 25.0 percent by weight of the alloy, and the nickel being present in an amount between about 0.5 to about 0.6 percent by weight of the alloy. Heat treatment of the alloy causes a visually observable blue coloration.
    Type: Grant
    Filed: July 2, 1991
    Date of Patent: November 17, 1992
    Assignee: Ludwig Muller S.A.
    Inventor: Ludwig Muller
  • Coloring a gold alloy
    Patent number: 5059255
    Abstract: A gold alloy comprises at least gold, iron and nickel, the gold being present in an amount between about 74.4 and 94.5 percent by weight of the alloy, the iron being present in an amount between about 5.0 and 25.0 percent by weight of the alloy, and the nickel being present in an amount between about 0.5 to about 0.6 percent by weight of the alloy. Heat treatment of the alloy causes a visually observable blue coloration.
    Type: Grant
    Filed: April 17, 1990
    Date of Patent: October 22, 1991
    Assignee: Ludwig Muller S.A.
    Inventor: Ludwig Muller