You have the option of making some or all of your coins private. You further have the ability to make just some individual coins private or an entire album. When a coin is flagged private only you may view it while logged in to your account. The feature is a toggle, that is, you can switch back and forth from public to private by selecting the appropriate checkbox.
As another privacy feature you may hide the public display of the cost of your items. This option may be turned on or off in your User Setup preferences.