Thai significance for White Rose?

Nothing, I guess. Maybe it was just your girls' taste, she just love it because not so many white roses here in Thailand. During special occasions such as birthday, Valentines Day, some Thai students even give away black roses. I asked them why black and they told me, its just a beautiful color (unusual) and its a sign of good luck. If someone gave me black roses, I would be horrified ,but to Thais, its just the beauty of the color and nothing else.