Chaosmancer
Legend
Is the 5000gp diamond uncut?
Or has another crafter already spent a while crafting it? If its already cut then it shouldn't take over a year just to make a ring with a setting to take it.
I have no idea (per the rules) because the treasure in the DMs book just says Gems worth 5,000 gp and lists Diamonds.
It stands to reason that being in a hoard means that it would be a cut and polished gem, but it could be just uncut and worth that much, making it worth even more when properly taken care of.
And I completely agree with you that it shouldn't take that long, and I could completely say that the actual item being crafted is a metal band worth a gold at most (a gold coin probably has more metal in it than this ring since I'm assuming a small diamond) and so they are done in a day and add the jewel.
But a stricter reading says I am making a diamond ring, and therefore I need to craft based entirely upon the full price of the object. And, frankly, let us say it is a 5,000 gold uncut diamond and the player wants to spend their time cutting it and bringing out it's true value. Should that take over a year? How many actual gemcutters do you think spent over a year working on a single stone? That makes no sense, months sounds reasonably for something truly spectacular, but spending much more than that means they have no inventory and therefore no one can make jewelry and there shouldn't be these immensley valuable items in the hands of these wealthy nobles and dragons. Heck, we shouldn't even have all the diamonds that we buy for ressurection if they take nearly two months of work each. A high level cleric is going to probably buy an entire years worth of work in preparing 5 Raise Dead spells for his party members.
It just is a snarled mess in a lot of ways.