A crystal saw is an item made from a small crystal seed by invoking the singing bowl in Brimstail's cave in the Tree Gnome Stronghold. The seed is awarded to players who complete The Eyes of Glouphrie quest.
When in the inventory, the saw allows the player to build furniture up to 3 levels higher than their current Construction level. Note that this boost only works on furniture that requires both a saw and a hammer to make; as such, the saw cannot assist in building new rooms or planting flowers in a garden. This bonus stacks with all other boosts to Construction.
The saw has 28 charges (56 if the medium Western Provinces Diary has been completed). One charge is used each time the player constructs a piece of furniture while using the saw's invisible boost (so if you make a piece of furniture that you have the level to build, it will NOT use up a charge and will just act as a regular saw). Once the saw runs out of charges, it reverts to its seed form and will need to be re-enchanted by returning to Brimstail's cave or to Ilfeen (after Roving Elves).
If players lose or destroy the saw, they can get it back by talking to Brimstail in his cave. He will not give players a seed if they have either the seed or the saw in the bank or inventory.