A general rule of thumb is to limit gold to no more than 5% to 10% of your portfolio. Depending on your situation and your risk tolerance, you may be more comfortable with a larger or smaller share of gold in your portfolio. Most estimates suggest that investments in gold should account for only 5-10% of your portfolio and no more. This will ensure that your portfolio has room for other investments such as mutual funds, stocks, P2P lending, etc.
The research showed that the “sweet spot for the percentage of gold in the portfolio is 20%. In the long run, this provides the best balance between risk and reward. Many experts will tell you that you should keep your investment in gold limited to between 10% and 15% of your total portfolio. But this may not make more sense to you because we all have specific goals they're trying to achieve.