c.1840: 1 Troy Ounce Platinum (Imported? Market) = $ 6.80
c. 1840-5: 1 Ozt. Platinum (Ingot) = USD$ 7.50 - 8.33
In Boston , N.B. Chamberlain was likely selling English Platinum. (Platinum foreceps sold for the same price there in 1858.) Where Clarke's Platinum Forceps UK cost (1842) is known (equivalent of $1.83) and presuming the ratio of Retail Manufactured to Semi-Manufactured (UK Semi-Mfg Retail Platinum@$ 7.32) nearly identical:
1840: 1 Troy Ounce Platinum (Semi-Mfg, Ret.) = £ 1.50
1840: 1 Troy Ounce Platinum (Boston: Semi-Mfg) = $ 8.00?
Platinum Sponges and Coils for $ 0.25, Platina Forceps for $ 2. - 3. (212 - 258% more than UK Catalogue)
Citation: An introduction to natural philosophy: designed as a text book, for the use &c.; Denison Olmsted (1840)
Labor for Platinum Plate: $5.
Citation: Williams's New York Annual Register (1840)
c. 1840/1: Dr. J.G. Ambler began to practice dentistry in New York 1842; his preceptor was his uncle. If true, New York dentists manufactured their own Platinum (from Russian ore?) for dental plate.
c.1840?: Colombian Gold Ore was ~2.06% Pt