Probably the most distinguishing feature of Macadamia Nuts is their very hard shells. While the nut can be easily broken with a heavy hammer on a hard surface, the simple nut cracker which all other nuts yield to is not usable. The alternative to bringing a sledge hammer to the dining room table, seems to have been developed by German company Deluxe.
The solution lies in a small steel gadget and a circumferential slot cut in the nut.

This is quite an effective solution, although strong fingers and hands are needed to open the shells. The process mainly producers whole nuts unlike some more violent techniques.

Looking online shows that many different tools have been developed, some of them rather vicious in comparison.
The advantages of this technology as a cracker to be used by the eater, is diminished by the need to cut the nut before it is sold. There doesn’t seem to be any real advantage as cutting the shell opens the nut to degradation by air and insects.
Anyone want to make a comment – maybe the advantage lies in the cost and the novelty?

Was the circumferential slot make by the gadget of the picture?