I know nothing about Oklahoma where blackgold is operating (even had to look up how to spell it) other than the musical of the same name. Returns do seem extraordinary, but like Mercman the absence of the financial regulator's oversight would concern me. Quote from their website :
"Please note: This investment does not require licensing, authorisation, or registration with the Financial Regulator and, as a result, it is not covered by the Financial Regulator’s requirement designed to protect consumers or by a statutory compensation scheme"
I wonder how/why an apparently Irish company is involved in this? There is little information on the company itself on the website, and contact seems to be only thro a mobile number and email.