If there is one thing dwarves love, it is their metals and jewels. They are so known for their love of the underground fruits of the Mother Earth, that it is no small thing when a dwarf of high standing describes a woman as being more beautiful than "all the jewels that lie beneath the ground".
When it turns out that this dwarf is not only talking about a woman, but an elven woman, you know that something special is happening.
Elves and Dwarves throughout Tolkien works have not been on the best of terms. To understand why, you must go back in Middle Earth time to the era of King Thingol. King Thingol was given the great gift of the necklace, Nauglamir.
The Nauglamir was the greatest metalworking feat of the Dwarves. It was beautiful and comfortable beyond comparison.
Because Nauglamir was such a gorgeous (and comfortable) necklace, King Thingol asked the Dwarves if they would incorporate the Silmaril stone into the necklace so that he could have both near him at all times.
The Dwarves agreed, but only because they had their eye on keeping the final product for themselves. When the work was done, the Dwarves killed King Thingol, took the necklace and the stone and an all out Dwarves versus Elves war ensued.
Eventually the two races patched up their differences, but only just. They agreed that they did not like each other at all and left it at that.
When the Fellowship finds themselves at the edge of Lothorien, it is this barely bridled animosity that causes the elves of Lothlorien to initially declare that Gimli would not be allowed in wood. Even when they relent and decide that Gimli may enter, it is only under the condition that he be blindfolded. Gimli is by no means congenial back to the Elves and bristles at both them and their treatment.
This scene is meant to show just how much the Elves and Dwarves dislike each other and shows just how much of a leap of the heart it is for Gimli to fall in love with Lady Galadriel.
Oddly enough, though Gimli on more than one occasion in the book refers to Lady Galadriel's beauty, it is not her beauty that wins his love, but her heart and her kindness that does so.
Gimli finds himself in a land of restrained enemies and is already disheartened by both the deaths of his fellow dwarves and the death of Gandalf. Almost as if to rub salt into his wounds, Celeborn pointedly makes it clear that Dwarves are to blame for the mess the Fellowship found in Moria and, ultimately, for Gandalf's death.
It is Lady Galadriel who comes to the aid of Gimli at this moment. She defends the actions of the Dwarves, comparing it to what Elves may have done if they were chased from their own beloved Lothlorian.
It is in these words of kindness that Gimli looks up at an Elf and sees beauty beyond his imagination. He saw that her beauty was not only physical but to the core of her very being.
It is with this inner beauty that Gimli falls in love and pledges to pass that love down through his family's future generations.