There's a reason why you have never seen Kate Middleton or Princess Diana sport the hottest nail colors of the season. Instead, you have seen them step out in barely-there pale pinks or clear polishes on their nails.

Only natural-looking nails are allowed at official royal events — and even Queen Elizabeth has been wearing the same nail polish shade since 1989. For 28 years she's been reaching for the light pink shade called “Ballet Slippers” by Essie, which sells for a budget $9.

But that's not to say they can't bring out the nail art when they're at home — it's just that they can't go anywhere official with it on.

Tiaras are usually worn during white-tie affairs (which are the fanciest of fancy events), but not everyone can don one. Traditionally, they're worn for the first time by brides, and then by married women only, so you'll never see a single 20-something princess or a little girl wear one.

The reason for this, though, is kind of funny. "For married ladies it was a sign of status and would show you were taken and not looking for a husband," etiquette expert Grant Harrold, known as the Royal Butler, shares with the BBC. "For the gentleman it was a clear sign not to make advances toward the lady in question."

The royals use their purses and handbags for a lot of clever reasons and social cues, but no one as much as the queen. When Her Majesty wants the room to know that she would like to leave dinner in the next five minutes (meaning everyone else has to stop eating, too), she puts her bag on the table, signaling the party is soon over.

On different occasions, she uses her purse as a signal to pull her out of a boring or awkward conversation. When she moves her bag from one hand to the other, that's a cue to her aides that she's tired of talking to someone and they should give her a polite way out.

While Prince George looks adorable with his shorts and knee-highs, that's actually not just his mom's preference when dressing him. Young royal boys actually aren't allowed to wear trousers until they hit around eight or nine, signaling approaching manhood.

Originally, this tradition dated back to the times of breaching in the 16th century, when young boys wore dresses until the age of eight. Then in the 19th century, gowns were swapped out for shorts, giving us Prince George's aesthetic.

But there is also a more modern reason why royals dress their boys in shorts. Shorts are a silent British class marker signaling they're aristocrats, since trousers are thought to be "suburban," and no royal would want to seem middle class.

You might have noticed Queen Elizabeth's penchant for colorful, almost neon, monochrome outfits. While at first glance it seems like she must really enjoy color, it almost seems weird that her outfits can be so flamboyant, especially considering the Crown's feelings about nail polish.

It turns out the queen puts on such loud colors so the public could see her through the crowds. She's the main reason why people come to many of the official events, and it would be a pity if they couldn't find her in a throng. She was even quoted as saying, "If I wore beige, nobody would know who I am."

When traveling abroad, every royal member must pack an all-black outfit in their suitcase in case of an unexpected death. Remember, they must always look presentable, and it wouldn't look right coming home wearing normal clothes after a family member passing.

This became a rule after Queen Elizabeth had to rush back from Kenya in 1952 after her father, King George VI, died and she had to wait on the landed plane a few hours until someone brought her a change of clothes. It wasn't seen as proper to emerge in London with her normal dress after the sitting king had died.

Cleavage is a no-go for the women in the royal family, but sometimes the telltale line pops out when you bend over or get out of a car. Even that would cause a scandal, but there's a way around that: cleavage bags. Princess Diana was infamous for them, where she would use her clutches to hide the front of her dress every time she hopped out of a car.

The thing was, that was the only reason she wore them. They were so small not much would fit in them, but she knew she needed a stylish tool to keep the paparazzi from peeking down the front of her dress. In fact, she would meet with one particular designer before every event to design an appropriate clutch.

Anya Hindmarch, the designer, told the Telegraph, "We used to laugh when we designed what she called her 'cleavage bags,' little satin clutches which she would cover her cleavage with when she stepped out of cars."

For all royal events, the queen wants all her family members and guests to wear tights. So, even if you see a royal with a midi dress on with bare legs, they aren't actually bare; they have on a sheer pair of pantyhose.

This one's funny because there's no other reason for the rule other than the queen doesn't like wedges. She simply doesn't care for them and doesn't want your cork shoes anywhere near her when you come to visit.

For example, Middleton has been seen wearing wedges plenty of times for events and outings, but not when the queen is present.

"The Queen isn't a fan of wedged shoes. She really doesn't like them and it's well known among the women in the family," a royal source told Vanity Fair.

And wedges aren't the only thing banned from her Her Majesty's presence. Things like garlic and pasta are banned from the Palace because she dislikes them, and she's the ruler, so what can you do?

You probably haven't noticed this, but when Middleton or Markle shows up to an event wearing a coat or coat-dress, she never takes it off while there. The reason for that is that taking off a coat is seen as an unladylike action, and not fitting for a duchess or princess.

Queen Elizabeth always has a hat on that looks like someone's Sunday Best, and that's not only because she thinks it ties together her outfit. According to Diana Mather, an English etiquette expert, the queen is frequently seen in hats because of an old tradition barring women from showing their hair. A hat covers their bare locks up.

While royals are no longer obligated to wear gloves, the white accessories historically symbolized purity and status. Even when the tradition was commonplace, Princess Diana rebelled against it because she didn't like the impersonality of the message. She liked to hold hands when visiting people, or make real contact when shaking hands, so she refused to slip on the white gloves. She also stopped wearing hats because, “You can’t cuddle a child in a hat.” There goes my heart melting.

This is a sweet tradition that almost goes back two centuries. The flower represents love and marriage, but that's not the only reason royal brides put a sprig of it in their bouquet; it's also included because it's directly picked from Queen Victoria's 170-year-old-garden, making it a family affair.

Women aren't allowed to wear hats indoors after 6 p.m. for a very good reason: That's when the tiaras come out! This rule gave women a chance to gracefully swap their demure hats for something a little more flashy, putting on their family jewels with their evening dresses. Also, tiaras aren't allowed to be worn during the day, so the evening hours are the only time women had a chance to don them.

It's a common known rule that you're not allowed to touch any member of the royal family unless they make the first move. So, if they don't extend their hand for a handshake, then you're not allowed to thrust yours out and demand a greeting. However, it can still be a little awkward standing there, knowing the other person wants you to make the first move, even though you don't intend to.

In order to side-step that social awkwardness, many women in the royal family carry clutches with both hands. If their hands are occupied with their bag, everyone registers that there will be no touching and there are no hanging questions. Middleton is especially a fan of this move, often times appearing with a stylish clutch to match her outfit.

They're no longer forced to wear gloves at black-tie events, but if a royal did choose to show up with the accessory, there's a whole host of rules on how to properly don them.

You wear them when you're en route to an event, when shaking hands, standing in a receiving line, or dancing.

You have to take them off when you're eating (even if it's just a quick canapé or nosh), and they're forbidden at the dinner table. To take them off, you have to pull them finger by finger, and then rest them on your lap underneath your napkin.

If you look closely, sometimes the women wear colors to honor the country they're visiting, like Middleton wearing a Maple leaf hat when visiting Canada or the queen donning jade green when going to Ireland.

From having to wear tights for the rest of your life to be careful not to offend with your cork wedges, Markle is in for an interesting sartorial ride.