How much is 19 grams of 9ct gold worth?

The price of gold fluctuates so much it's almost pointless to give a specific value. 1 dwt is about 1.5 grams, so if you multiply the current gold price per gram (which you can get from the financial section of any major newpaper) by 1.5 that should give you an approximate value. Or you could divide the price per ounce by 20, since there are 20 dwt in a troy ounce.

(note: 1 dwt is actually 1.55517384 g, so you can get a more accurate value by using more significant figures.)