木 目 金
We English speakers tend to refer to all hada (grain patterns) that resemble woodgrain as mokumé gané. The terms for describing hada were originally applied primarily to the patterns visible on the ji of swords, the area between the edge of the blade and the blade ridge (the ridge running the length of the sword, halfway between the sharp edge and the dull back). This pattern was referred to as the jihada (ji+hada). There were a number of different patterns, formed by different methods of folding the metal:
- Itame -- woodgrain.
- Masame -- straight grain.
- Mokumé -- burl grain (lit. 'wood eye')
- Ayasugi -- undulating grain, more fluid than strait grain, but less turbulent and broken than wood grain.
- Muji -- no grain, no visible pattern.
Most of the metalwork found today would indeed fall into the mokumé category, although you might also find itame or ayasugi on some pieces. Mokumé gané shows the effects of the mixing metals at their most striking; earthy and organic, but still metallic and well defined. Despite the popularity of these patterns on modern jewelry, you will never hear the words itame or ayasugi used; they are all mokumé now.
Gané means metal in Japanese, and can be appended to any of these descriptors, although one usually does not do this when talking about swords, and you are unlikely to be using any of these words in English unless you are talking about swords.
Thanks to liveforever for the kanji.