I haven't had this one in a while, but it looks like Gardenia taitensis 'Heaven Scent'. Confusingly, there is a Gardenia jasminoides cultivar with the trade name of Heaven Scent®.
I think Diamond's Fragrant Delight looks similar also.

Thanks Dar, i have Gardenia taitensis 'Heaven Scent' and it is double. This one is single petal. It is not jasminoides because this one has broad leaves. It probably is gardenia hawaii or taitensis classic or maybe you are correct Diamond's Fragrant Delight.

Khabbab,

'Diamond's Fragrant Delight' seems to be a name invented by Logee's and I wonder if what they have there is really what others call 'Heaven Scent'. The flowers of 'Heaven Scent' can be single too but often have those smaller petaloids in the center just like 'DFD' as seen in Logee's catalog.

I did some searching and found this passage below.

"One of my proudest plantaholic moments was when I discovered a new variety of gardenia -- just call me the Queen of Green! I was on a tropical vacation a couple of years back, and stumbled across a glossy leaved gardenia with huge, thick, satiny white blossoms, with a perfume that was sweet, spicy and strong. I took cuttings, and that plant is now available exclusively from Logees Tropical Plants, and they even named it my honor, 'Diamond's Fragrant Delight'!"
Source: http://www.huffingtonpost.com/mike-diamond/the-begonia-monologues_b_3951541.html

Perhaps there could be various selections of G. taitensis with in cultivation.