I always like it. ask your girlfriend if she never buys more silver. will she suddenly have 2 silver? or maybe 4 silver. does silver multiply in the basement somehow?

then ask her if she wants to buy something that one day turns into two and maybe another day turns into 4. then pull up a chrat of stock splits. and show her that yep stocks split if you own one share eventually you might own two shares. it would be cool if you then explained how buying a basket of stocks throuhg a fnd is better because some might go down but the ones that go up are really going up.

however word of caution. i found you can never change a persons mind about money. and i have found lots of people use the wrong words for things. and i found that lots of parents generally take from their children. my grandma recently took some fancy knives i had purchased because "he will not need them"

one line i like " i bought this bag of chips i will eat them wherever i please because they are mine", your gf earned her money and will do what she pleases with it. if you try to have her do something different she will be resentful.

tl:dr; i would try but do not get your hopes high that you can change her behavior.