IQ based, karma, takes 1 week.

The character must carry the item on his person for a week, devoting one hour of study to it per day.  At the end of that time, roll Item History with a penalty determined by the item (scales roughly with the spiffiness of the item).  Success reveales the item's key knowledges, up to a maximum of one key knowledge per rank.

This is usually also helpful in determinging what the item is useful for.