The official GemStone IV encyclopedia.
A ghostly instrument is an ethereal or spectral instrument that can be summoned from a pin.
You analyze your tambourine pin and sense that the creator has provided the following information: You can RUB this pin to summon a ghostly instrument. It has plenty of uses remaining. Willing merchants may be able to recharge it. It currently produces an instrument as follows: a spectral tambourine The appearance of both this pin and the instrument it summons may be altered with a LONG, SHOW, or both. The instrument must remain ghostly, spectral, ethereal, etc. and maintain a noun suitable for its type. You get no sense of whether or not the pin may be further lightened.
When the instruments leaves the caller's hand, be it dropped, stowed, or otherwise put away, the instrument will dissipate.
Your spectral tambourine dissipates.