For the record: I don't own any of it!
"I hope you are enjoying the milk?"
Newt's niffler shrugged and seemed to waggle a cheerful acceptance of the refreshment.
Albus tried not to feel awkward; tea etiquette when one's partner was a fuzzy woodland creature was certainly a new endeavor for him. He had breezily asked the niffler to tea, but rather expected to socialize with Newt and his creature. He meant to have a chance to learn more about this small but impressive creature, one that was reputed merely to covet anything shiny but had apparently just demonstrated far more subtle tastes. He much doubted that the amulet he had made with Gellert long ago was the most sparkly object in Paris, and yet it was this treasure this creature had unerringly scented and, from what he gathered, crawled through a fiery battleground to seek for its trove.
Had it not done so, on its own initiative, all could have been lost.
"I had meant to ask a few questions of your master... no?" The niffler's thick fur had fluffed up indignantly.
"Your... handler? Keeper?" A snort answered.
"Your Newt." The niffler sniffed acceptance of that title.
"You do seem to understand what I'm saying, don't you?"
He wondered where a niffler would've learned to roll its eyes.
"Perhaps you can answer my question, then. If you would." He took the amulet from his vest pocket. "How did you know?"
The niffler shrugged a little, as if to say: it was obvious.
"You sensed this and slipped away from Newt; I'm certain he walked by at least a few dozen diamonds, being in Paris, but those didn't tempt you as this did."
The niffler's mouth seemed to water a little at the word 'diamonds', but its eyes stayed on the amulet. It was a look that reminded him of a 'bloodhound', like in the stories from that Muggle magazine from London, the ones penned by that clever Doyle chap...
He took a paperweight from his desk drawer, made of gilt and glass; sparkly but cheap. The niffler's eyes stayed unerringly on the amulet, the drops of blood suspended within. It shuddered in confusion, sniffing the air.
"The blood oath is still... more shiny, then?"
The niffler shook its head briskly, then, to his surprise, opened its little pouch of treasures and pulled out a moving photograph, laying it flat on the table. Albus peered at it upside-down and smiled. It was Newt, seated in a chair and beaming ear-to-ear at the camera, a nest of towels and linens sheltered upon his lap; within the circle of cloth was another adult niffler- if the specimen sharing his tea was also a mature one- and two or three tiny, hairless newborn pups peacefully suckling. Another pup had finished its meal and was adventurously attempting to scale the front of Newt's shirt. His guest was seated on Newt's shoulder, a sentry position watching over the nest.
The niffler emphatically nosed at the picture, dismissing both the blood oath amulet and the gaudy paperweight with a disdainful little flick of its beak.
"Your family? They're beautiful," he complimented gently, quickly replacing the words 'absolutely adorable' with something more respectful and less diminuitive. The niffler glanced at the paperweight, then back to the photograph, as if to emphasize the point: no contest at all. "They are not sparkly... but they are what's most important," he translated, slowly. "You scented that this amulet was important... that it was deeply meaningful; valuable, though not like diamonds."
The niffler nodded.
He wondered if Newt had yet apprehended this facet of niffler development and maturation, if it would appear in the next edition of his thoroughly charming book.
"Your kind are thought merely to scent that which is sparkly in appearance, but as you become older and more experienced, your palate becomes more discerning, does it not? Seeking out true value, not the mere appearance of it. Does that sound right?"
The niffler indicated his photo, then the paperweight. "Your children would quite enjoy this bauble, I'm sure; to the younger of every species belong the simplest, purest pleasures. Would you like to have it? I do rather owe you for this." He put the amulet back in his pocket.
The niffler looked longingly at Albus' collection of instruments, then indicated the photo.
He was no Unspeakable, but curiosity for the great Mysteries had always been a cherished hobby, and he found that having the bizarre-looking metal contraptions on display also leant him an air of mystique as a professor; he'd overheard no fewer than five different student theories as to what any of them were actually for.
Why would the niffler be interested in them in connection with his family, though, as a reward better than a sparkly toy? He tried to see them through the eyes of a creature attracted by shiny and valuable things, but devoted to something that was far more precious than any gemstone.
He supposed all the metal bits were rather... sparkly.
And suddenly he saw it.
Decades afterward, the grey and wizened Headmaster of Hogwarts would gaze around his office and remember with a smile the finest purpose to which all his glittering instruments, the trappings of academic curiosity, had ever been turned: the ultimate playground for a crew of utterly ecstatic baby nifflers.