Are "hard money loans" meant only for real estate?

From Wikipedia:

A hard money loan is a specific type of asset-based loan financing through which a borrower receives funds secured by the value of a parcel of real estate. Hard money loans are typically issued at much higher interest rates than conventional commercial or residential property loans and are almost never issued by a commercial bank or other deposit institution. Hard money is similar to a bridge loan, which usually has similar criteria for lending as well as cost to the borrowers. The primary difference is that a bridge loan often refers to a commercial property or investment property that may be in transition and does not yet qualify for traditional financing, whereas hard money often refers to not only an asset-based loan with a high interest rate, but possibly a distressed financial situation, such as arrears on the existing mortgage, or where bankruptcy and foreclosure proceedings are occurring.

This implies to me that these loans are only against real estate. Presumably, because it doesn't move and can't be simply taken away, as in the case where you have say, a high value diamond or painting.