It could have been the phenomenon known a “halo”, attributed to holy or very spiritual people. Think how Jesus is portrayed in paintings with the glowing ring on top of his head… that is is the artist’s shorthand for this attribute.
All of the world’s most major religions refer to it. It makes for interesting reading, if you’re interested.
It’s less about skin and more about radiating an inner spiritual light.
This person may have been in a different state of consciousness, not visible to the naked eye… literally perhaps even different brainwave patterns (this has been studies in monks in monasteries).
She may have been in a state in which she was radiating so much deep, peace, love, gratitude, and good intentions… that your subconscious read this as a literally “beaming”… but as you said, this does not make the skin shiny nor glittery, but there is an unmistakable glow and brightness.
It’s the same in very dark skinned people, too.
If you want that kind of glow… then engage in the perfection of your character… you will begin to glow, too. Fasting helps, too. Basically, what would Jesus do? Good place to begin. Love thy neighbour, be charitable, forgive the people, etc etc…
Incidentally, it may not necessarily be the case that this person is involved in a formal religion, they may not even be aware they have this effect or appear this way, but they may have the most extraordinarily soft and loving heart.
I wish you all the glowiness in the world.
I feel a bit envious you got to see someone like that!