Personally, I do not see it as a big deal. Life is too short to complain about how little gold your MIL got you. You have your whole life in front of you to enjoy, don't let something like this hold you down. :)
If the gift is not very useful to you, do the right thing and donate it to a good cause or a charity. What a beautiful way to start a married life, to share with those less fortunate, those who will probably never touch gold.
Plus, your Husband to Be will shower you with gifts, I am sure. Don't worry about the MIL so much! Sometimes they can be Stubborn!
It seems many on this board would be dissatisfied with their partner if he/she could not purchase them expensive items...well maybe you should consider an arranged marriage with a very rich person. You may not find true love, but you will have plenty of shiny things, after all...isn't that all you need in life?:(