DIAMONDS - a luxury good or an "attractive" investment (alternative)?

I was inspired to write this article by FOUNDER @DoktorCukrzyca with his question: Can an investment in diamonds be a better hedge than gold? Is gold or diamonds a better inflation hedge? I expressed my opinion on the usefulness of gold in the context of protection against inflation in an article published in the News at this link: https://beta.ccfound.com/news/2900/zLoto-inwestycyjny-hit-czy-niekoniecznie. I am not an expert in diamond trading, but the question was so interesting that I decided to check whether diamonds can be considered as an investment asset. In order for an "investment curiosity" to be consciously included in the investment category (especially in the category of securing capital against inflation), it must meet certain criteria. In addition, such an asset should be comparable to another asset (in this case gold) considered in the same context. What specific criteria do I take into account? The answers to the following questions will be helpful in this regard: 1. Can diamonds be considered an investment or rather should they be treated as luxury goods? 2. Which diamond will actually provide capital protection against inflation: premium grade or commercial grade diamond? 3. Should I buy Diamond, Emerald or Asscher? 4. Is it better for a diamond to fluoresce and at what level, or rather not? 5. Should I buy a GIA, HRD or IGI certified diamond? 6. If I opt for a certificate issued by a local jewelery institution, how important will the reputation of a specific local appraiser be for the reliability of the valuation? 7. Are there any standardized diamond price indexes to estimate the correlation of diamond prices with inflation rates? Can I keep track of changes in the spot price of diamonds free of charge? 8. How to assess liquidity in the commercial diamond market and premium market? 9. How to assess the relation of supply to stocks on the diamond market, which in the case of raw materials (e.g. gold) directly translates into a potentially low-inflationary nature of a given raw material? 10. Can a Polish small retail investor successfully gain exposure to the commercial and premium diamond markets?