Not surprisingly Diamonds are symbols of wealth. They also attract abundance - the larger the diamond, the more wealth they attract. :)
Carnelian can be placed near your front door to invite abundance into your home. Aventurine's bright positive energy also attracts prosperity. Other crystals to attract wealth include Green Tourmaline, Hawk's Eye and Moss Agate, and more precious gems such as Ruby, Sapphire, and Topaz.
Crystals amplify our energy and intention, so the more we direct that energy to our desired outcome, the better the results. It is also important to explore any resistance you have to receiving and about money, as these will only sabotage your efforts if left unaddressed. A Crystal Healing might be a good idea to help clear these blockages, balance your energy flow, and heal self-worth issues.