UK, 1873-85: Platinum Price Estimated to Gold

1872: One Troy Ounce of Gold = £ 4.24
1872: One Troy Ounce of Silver = £ 0.2469

1872: One Troy Oz. of Platinum ~ £ 1.23 - 1.41

1873: 1 Troy Ounce Platinum (manfactured, retail) = £ 1.60 (USD$ 8.88)

1885: One Troy Ounce of Gold = USD$ 20.67

1885: One Troy Oz. of Platinum ~ "half the price" = ~ USD $10.

1884:  1 Troy Oz "Platinum" (generic range: all types) = USD$ 8. - 12.

c.1872:

c.1885: