A coworker brought in some ruby grapefruits from her garden, these are the best grapefruits I have ever had. Each one is huge in size with beautiful ruby orange color. The fruit is juicy, tender and sweet. She said the tree started as a cocktail tree bearing oranges, lemons and grapefruits. But after a couple of years, the tree only produces grapefruits.

Could anyone please advise how we could propagate the grapefruit? Should we plant from the seeds, or use cutting, or else? Any advice will be very appreciated.