It looks like it could be genuine. It is difficult to tell.
Take it to a jeweler and get a precise weight, accurate to 0.1 gram. Genuine coins weigh 27 grams. If yours weighs this amount, that is another indication of authenticity. If not, well, you know.
The coin comes from Peru, with a date (I believe) of 1708. It could be an 8 reales or an 8 escudos. Both these coins use this pattern. The 8 reales is made of silver, and the 8 escudos is made of gold. Again, it is difficult to tell from your photos.
If genuine, 8 reales are worth around $100 US dollars, while 8 escudos are worth around $3000.
If a jeweler says 27 grams and gold, then you should have your coin authenticated by a professional. Look up one of these on the web: PCGS, NGC, ANACS, ICG.Reply