After researching I did not found a famous quotation related to your
request, so I worked on the translation of your original phrase and I
got this for you:
"Cave aurum, nam id quidem amicos optimos mutare [or vertere] in inimicos potest"
Here are some explanations:
Comments below suggested you "Caveo aurum", that means "I beware" so I
prefer "Cave aurum" which means "Beware of gold!". You can find a
similar construction in the famous inscription at the entry of Roman
houses "Cave canem" which means "Beware of the dog!"
You can use "pro" instead "nam", but there is a significant difference
between these words; "pro" means 'on (in) behalf of' so "nam" [(conj.)
for] is more appropiate in this case.
"quidem" is the proper adverb, many missuse the word "etiam" that is a conjuction:
Mendaci homini, ne verum quidem dicenti, credere solemus.
Liars aren't believed even when they are telling the truth.
(Cicero, De divitatione)
Pericla timidus etiam quae non sunt videt.
The fearful one sees dangers even that are not there.
(Publilius Syrus, Sententia 452)
You can also use "vertere" instead of "mutare", here is your choice, I
feel that mutare more meaningful for modern English speakers.
I use "potens" because it express in a more enphatic way the power to
make the change than the use of "possibile est".
For better understand of meanings, etc. see the following page and links on it:
"Latin Dictionary and Grammar Aid":
For mottos and examples see the following pages:
"Sententiae Latinae -- Latin Maxims":
"Famous Latin quotations, translations, phrases, latin to english,
quotes, sayings, US Armed Forces mottos":
"Latin Quotes, Latin Phrases, Latin Mottos and Latin Quotations":
You can also try a demo version of QuickLatin:
Use of QuickLatin and Words programs to help me with the translation.
Use of the online dictionaries for the same.
Used my own (very low) knowledge.
Search on mottos and phreses for similar constructions (with no much success).
Used the following keywords at Google.com to find the helpful pages:
latin english translation
latin "beware" "gold" turn
I hope this helps. Please feel free to use the clarification feature
if you find something unclear and/or incomplete before rate this
answer. I will be glad to give you further assistance on this if you