The golden spoons [were] twelve, full of incense
Which points at the use those spoons or cups were of, namely, to carry incense in them, such as were used on the day of atonement F12:
[weighing] ten [shekels] apiece, after the shekel of the sanctuary;
(See Gill on Numbers 7:14);
all the gold of the spoons [was] twenty [shekels];
which amounted to forty nine ounces, five drachms, scruples, and eight gains, worth about seventy five pounds of our money.
The Brenton translation of the Septuagint is in the public domain.