I honestly can't say for certain because I'm not familiar with darts at all. They are from Marlboro, and they usually have good to high quality items. I do not know the value of this set of darts. They are steel tip, and a quick look around the internet says that they are 17.8 grams / 18 grams. It seems they are likely nickel silver. There is no information provided with the dart packaging itself.
Here is a steel tip guide from Pro Dart Boards: http://www.prodartboards.com/steel-tip-darts