Many retailers are using lockable glass displays. These are clear retail display cases that can be locked with a key but showcase their products so customers can see them. This means shoppers would need a staff member if they want to handle the item. It is a frequent means used to secure costly stock.
This is how you mark the item you want to be treated securely. Go to stock maintenance and then catalogue; you will see a list of several specialised item categories. (See below) Tick secure.
There are plenty of other options marked, and I suggest you review them, too, as they may be helpful.