The 21 characters featured in this dingbat collection, Crowns and Coronets, are as detailed as you are going to find anywhere, never mind the fact that it's a dingbat font. I have only shown a handful of the available crown images here, so you can get a better idea of the quality we are talking about, but there are certainly plenty to choose from. If you want an image reminiscent of the Kings and Jacks found on playing card designs, then there's a couple of those thrown in, too.
You have the detailing you would be pleased to find in a book, and that would certainly be detailed enough for a school project, maybe on the forthcoming Royal wedding in the UK of Prince William to Kate Middleton. In fact, if you want the images for this purpose, then take a look at the collection of images of Prince William as a dingbat font detailed in the references at the end of the article.
Crowns and Coronets by Emerald City Fontwerks - Fontspace