Do you know that giving them a gift may make the difference between them making another referral or not?
It doesn't have to be something as elegant as this tower (unless of course the referral was worth a lot to you), it can be a handwritten note, a small token of appreciation like some delicious chocolates.
The concept of gift-giving seems like a bribe, but giving personalized corporate gifts now and then actually helps build and strengthen a business' relationship.
Corporate gift giving is actually quite common. Our company, Gift Basket Villas helps with personalized gifting by adding a company's logo, name of the company or salesperson or other identifying information so that the giftee remembers the giver. In this way, instead of just giving a cup with your logo, it's a beautifully wrapped gift that leaves a lasting impression.