The 19-year-old reality TV star splashed out on the 60-carat jewellery for her rapper beau, who turned 27 on Saturday (19.11.16), and he showed off his latest gift on her Snapchat account.
Kylie shot a short clip of Tyga wearing the impressive piece of bling and he gave her a big hug to say thanks for the present.
On Saturday, the pair headed to Arizona to spend time with pals and later that evening she treated him to a dinner date, for which she dressed to impress in a figure-hugging white outfit.
The blonde star had treated her boyfriend earlier in the day by sharing a topless picture of herself embracing him on his birthday.
She captioned the image: ''happy birthday baby (sic)''
Kylie added another picture of them both in a similar pose and wrote: ''Irreplaceable.''
Last week, Kylie threw Tyga an early birthday party and shared several videos of the bash on Instagram.
One showed her and fellow partygoers, including his four-year-old son King Cairo - who he has with former fiancée Blac Chyna, who is now engaged to Kylie's half-brother Rob Kardashian - wishing him a happy birthday and surprising him with a cake.
Cairo was stood on a table surrounded by balloons while Kylie held onto his waist, and another clip showed the youngster giving his father a painted ornament with the word ''dad'' on.
In the video Tyga said to his son: ''Aw thank you man! Gimme a high five, gimme a high five!''
He then picked the little one up and gave him a warm embrace.
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