You can feel it in your heart that the timing is right - you're going to propose! And because she is "the one", you have decided that your special lady should receive an engagement ring that is as beautiful, special and unique as she is - a diamond ring.
However, it is fair to say that most men (regardless of how well they know their girlfriends) are not blessed with great knowledge when it comes to buying engagement or wedding rings. Therefore, you may have to do a bit of detective work to ensure you pick a suitable ring from the myriad of different diamond engagement rings that are available.
The best way to gain a bit of insight into the type of engagement rings she might like is to take a sneaky look in her jewellery box. Does she prefer to wear gold, or are her rings made from white gold or silver? Does she like large jewellery pieces, or are here items understated and subtle? Knowing the answers to these questions can help you to determine whether your special someone would like a big rock or a modest stone on her finger.
However, if a good root through her jewellery box still leaves you none the wiser, you can always turn to a sister or close friend. Indeed, close female companions tend to have a good idea of each other's style preferences, so looking at diamond rings with them in tow could be very helpful indeed.