The Pope gave Charles a piece of the ‘true cross’. Christ! What present do I get him now?

What does a Pope buy a King? What do you get the man who has 10 castles, 56 royal cottages, and a personal fortune estimated to be upwards of £1.8bn? Fist-sized diamonds? Greenland? A joke book?

In the case of Pope Francis and King Charles, the pontiff has opted for two splinters of wood – splinters that the Vatican believes were taken from the cross on which Jesus was crucified. The little relics – about 5mm and 10mm long – will be mounted on a newly crafted cross called the Cross of Wales, which will be carried at the head of the coronation procession next month. What do you get the man who has everything? A cross to bear, apparently.

Some 500 years since Henry VIII was excommunicated by Pope Paul III, it’s nice to see old friends burying the hatchet. But it’s also a perilously high bar to set. How is Charles meant to respond in kind? Quest for Excalibur on eBay? Fork out fistfuls of dollars for the Turin Shroud?

When the planet’s richest people go shopping for each other, they have an even harder time than we do. Hollywood, for instance, goes wild for whimsy. When Kanye West and Kim Kardashian tied the knot in 2014, the rapper reportedly snapped up 10 European Burger Kings for the reality TV star as a present. “She owns all the jewels anyone could ever want,” said one insider. “So he is taking the practical route by investing in businesses for her instead.”

Lady Gaga presented the horror director Ryan Murphy with a bag of her own vomit when she starred in his show, American Horror Story: Hotel. “He was like, ‘Oh, you think you can disgust me? You can’t,” she said.

The scatological might not pass muster with the royal family. Then again, the good people of Fiji presented Queen Elizabeth II with a tabua (the polished tooth of a sperm whale) every time she visited, and she seemed to enjoy it. We’ll say less of the straw penis sheath which Prince Philip received from the folk of Tanna, in the South Pacific.

Forget diamond rings and £40m Cartier bling – the “have yachts” already have yachts. Go broke for something personal. At the royal Balmoral get-together, Prince Harry once famously gifted the Queen a shower cap emblazoned with the words, “Ain’t Life a Bitch”, which went down a storm. So too did Charles’s leather toilet seat cover, courtesy of his sister, Princess Anne.

We live in an age of stealth wealth, one in which the elite dress down in jeans and in which lavish excesses of old are deemed to be tasteless. The last gift His Holiness received from Queen Elizabeth II was endearingly personal: a hamper of produce from the royal estates, including honey from Buckingham Palace, a haunch of venison and a dozen eggs from Windsor, handmade aromatherapy soaps from Sandringham and, somewhat perplexingly, Welsh rarebit smackerels from Fortnum & Mason.

“Honey from my garden – I hope that will be unusual for you,” she said. Touching. The refreshingly frugal Pope Francis is a man who still zips around in a battered Ford Focus rather than the customary bulletproof limo. It pays to show your working.

The best gifts enrich us. They’re stories that we share. They say something, whether it be profound, trivial or endearingly silly, about the bonds between us. Good gifts show that you have paid attention. Bad gifts make you wonder if the giver knows you at all.

Lord Salisbury, Queen Victoria’s prime minister, presented Her Majesty with a gift to mark her golden jubilee. It was a portrait of himself. That says a lot. Whatever your persuasion, I imagine that Pope Francis’s offering strikes us as rather more selfless.