Summa pulchritudo mea donum mundi est

Latin lessons at the Efteling.

Visiting the fairy tale display on "The Emperor's New Clothes," (De nieuwe kleren van de keiser) and I'm confronted with the inscription below. Of course my wife looks to me for translation and I'm baffled. My Latin was never very good in the first place and it's getting to be 20 years ago, after all.

Summa pulchritudo mea donum mundi est 

-Caesar Narcissus

This is a situation where the overriding meaning is clear ('My incredible good looks are god's gift to the world'), but I can't get make the words in front of me say that and remain true to what I honestly suspect are the individual word meanings and cases.

Anyhow. In the cold light of afterward, I find pulchritudo is a 3rd declention noun (feminine), so pulchritudo is the presumptive subject, which is good, and most of the rest falls in place.

"Summa pulchritudo mea" all group together, "My most-high beauty,"

The "est" could have been left off, but there it is: "is."

"Donum," gift, is also nominative, (2nd declention), not accusative as I dimly feared, and I'm almost home:

"My great beaty is a gift".

But there's the "mundi," which I would really have liked to see in the dative, "mundo," = "to the world," or "for the world."

But what we have is "mundi," genitive. Doesn't make much sense intuitively. Gift belonging to the world?

After some refresher Latin grammar Googling, I'm reluctantly calling this "mundi" either a "subjective genetive" or "objective genitive," because a gift raises the idea of a receiver.

I can't find any examples of this _ on the contrary I see donum taking a dative everywhere _ but I'm assuming whoever they let make humorous signs at the country's biggest tourist trap attraction knows more than I do.

So:

"My incomparable beauty is the world's gift." (Subjective genitive, leading candidate for correct translation)
or
"My incomparable beauty is the gift of the world."(Objective genitive)

Either way, I still think it would make more sense with "mundo," given the story.

"My incomparable beauty is a gift to the world."

Latinists? Another use of the genitive I'm not considering? Other possibilities/errors?