Rainbow Grapes !! wOw
It is not a hybrid or any species of grapes. They get their colors during a process called veraison that occurs when they start making sugar and are known for their incredibly delicious flavor.
Hoax or Fact:
Various pictures of what are shown as 'Rainbow Grapes' have been shared online with the accompanying messages saying the rainbow colors are naturally formed in grapes during a process called Veraison. The claim is only partially fact.
Veraison is a viticulture (grape-growing) process meaning "the onset of ripening," involving change of color of the grape berries from growth to ripening. During this process, the grapes cycle through various colors, and at the end of ripening, they all usually display the same color. Like shown in the story, grapes do not come in rainbow colors as such. In the video, an expert describes how Veraison process involves change of colors in various types of grapes.
The change in color of grapes is presumably because the chlorophyll is broken down. As ripening continues, the grapes become attractive to animals due to changes in aroma from acidic to sweet with fruitiness.
Worth1000 Photo Edits
The first two pictures that come with the story of rainbow grapes are actually taken from photo editing contest of Worth1000.com that can be seen here and here. The pictures were entries to 'Color Blind' contest, where participants were to create images with colors that are a bit off. You can see the original grape pictures in Image Gallery. The other two pictures appear to be genuine examples of grapes in the veraison stage.
People should be aware that some online vendors sell the purported 'rainbow grape' seeds using deceptive images like the ones shown above.