Your question makes me think of Theda Bara, who was known for wearing very revealing costumes in her post WW1 films. It was popular at that time to promote an actress as mysterious, with an exotic background. The studios promoted Bara with a massive publicity campaign, billing her as the Egyptian-born daughter of a French actress and an Italian sculptor. She was a silent movies actress, & one of her films was the 1917 version of Cleopatra.

I've attached a newspaper article I found on her Wikipedia entry, which best demonstrates what I mean. And yes, the famous Ptolemaic Queen of Egypt, Cleopatra, one of the Hellenic (Greek) Ptolemy family, did get around in chariots of some sort. I doubt that the fantastic giant Sphinx-like throne, with steps leading up to it, & hauled on rollers pulled by Egyptian slaves, portrayed in René Goscinny 's Asterix comics ever really existed outside his fertile imagination, though. 

Hmmm, I wouldn't want Jadis's outfit to be too revealing — it's a children's story, and the film is going to attract a young audience even if Netflix decides to pitch it at an older one. Different cultures have different standards on what is appropriate for children to see, but film-makers are wise to lean pretty conservative in that regard if they want the production to have a broad audience without a whole lot of controversy over whether or not it's "family-friendly".

All we're told about her clothing in the book, of course, is that she has "bare arms" and Digory's rather elderly Victorian-era maiden aunt does not approve. It's still only 1900 in England in this story, so we're implicitly left to imagine how scandalised Aunt Letty and many others would be if Jadis wore anything even skimpier than that!!

But another side of it is, I think, that while Jadis is tremendously proud and conceited and very well aware of her outward attractiveness — she imagines, at least at first, that Digory's uncle must have "seen the shadow of [her] face" through his magic and "for love of [her] beauty" sent the children to find her — we don't ever really see her using her beauty in a seductive way to win people over. I can't imagine her ever having, or wanting, a husband or romantic partner, or even pretending to want one in order to get what she wants. She seems to be of the mentality that everybody, simply upon seeing her, will be so overwhelmed by her beauty, or her terrifyingness, or both, that they'll instantly fall down before her and do whatever she commands. (And if they don't, she'll "blast" them, or — after she loses her ability to do that — at least cause serious damage.) So, even if this wasn't a film that has to be appropriate for under-12s, I just can't see Jadis putting on any sort of "exotic performer" attitude that exploits her physical beauty in order to seduce those she sees as her subjects. (And to her, everyone else is inherently her subject.)

As for what she should wear, I've always imagined her pretty much as Pauline Baynes portrays her and I'd like to see a costume something like that — I like what @icarus says, "eerily familiar... but yet still completely other-worldly and new." Definitely something eye-catching, but still with the understanding that her personality, not just her physical appearance, is the important factor in the story.

Tooting my own horn here, I did a whole series about the appearance of Jadis and Charn on my website:

http://www.cobaltjade.com/2021/08/all-things-charn-part-v/

Generating AI pictures of Jadis is also a hobby of mine

Charnian crowns

Costume 1

Costume 2

@Courtenay: Hmmm, I wouldn't want Jadis's outfit to be too revealing — it's a children's story, and the film is going to attract a young audience even if Netflix decides to pitch it at an older one.

That is just the joke of Theda Bara's newspaper outfit for Cleopatra, along with those early 20th century outfits she wore, which are fairly tame compared with what you see by today's catwalk standards. Theda Bara was daring enough by 1900's standards, & even Pauline Baynes' illustrations suggests that both Jadis & the actress would definitely be considered "brazen hussies" by Aunt Letty's standards. It also explains why Uncle Andrew would call her, a "dem fine woman".    Heaven knows what the likes of Aunt Letty would think of current newspaper standards! But I agree that even Elizabeth Taylor's Cleopatra outfits were a bit more modest by comparison.

@Cobalt Jade: I did a whole series about the appearance of Jadis and Charn on my website

I took a look at your pictures. The first costume was lovely, but more Elizabeth Taylor than Theda Bara. The second one I thought would be okay for Jadis, but I prefer the aggressive-looking spikey-looking crown Jadis wears in Pauline Baynes' illustration. Even the expression on the model's face makes her a reasonable Jadis.  

I would think Jadis’s Charn attire should not be too revealing, but her arms should be bare, given how Aunt Letty doesn’t approve of such fashion in the book. Given that this is set during late Victorian London, at the time, bare arms were considered the indecent by women like Aunt Letty and such.

Question is, what did the citizens in Charn wear? All we get that in the Hall of Images, Digory and Polly see the line of royals wearing fine clothing, robes, rich embroidery, and crowns. So could fashion have changed overtime in Charn up until Jadis speaks the Deplorable Word that destroyed every living thing except herself? Possibly, but then I don’t know. 

So Jadis should not wear anything too revealing, but it should be totally different than our world. 

I think I always interpreted Jadis' Charn outfit to be Persian-esque in design.

It obviously has elements of other ancient empires such as Egypt, Greece and Rome, but I think it's the vibrant colours, the spiky crown, plus that sort of floaty silk shawl that pushes it further East.

Not quite delicate enough to be Hindu, but too vivid for Greco-Roman aesthetics. Or something like that.

I tend to agree with @icarus about the impression of Persian influence but I also confess I looked at the image and thought of mermaids and coral reefs. 

Which given that Charn has dried up is an interesting angle to consider. 

Posted by: @mel

but I also confess I looked at the image and thought of mermaids and coral reefs

. 

Now.that you mention it, her crown does rather look like a little Octopus who got lost up there.

 @Courtenay: But another side of it is, I think, that while Jadis is tremendously proud and conceited and very well aware of her outward attractiveness — she imagines, at least at first, that Digory's uncle must have "seen the shadow of [her] face" through his magic and "for love of [her] beauty" sent the children to find her — we don't ever really see her using her beauty in a seductive way to win people over..... I just can't see Jadis putting on any sort of "exotic performer" attitude that exploits her physical beauty in order to seduce those she sees as her subjects. (And to her, everyone else is inherently her subject.)

Now that is a very fair point. Conceit, selfishness & taking her own good looks for granted, are hallmarks of Jadis. I don't think she really noticed anyone whom she considered below her in status. Definitely not the sort of romantic interest that Uncle Andrew, conceited and selfish, himself, should be bringing home to meet Aunt Letty, who sounds from the book, just like my grandmother, who, I remember, shared her POV about "bare arms".  

@ icarus: I think I always interpreted Jadis' Charn outfit to be Persian-esque in design. It obviously has elements of other ancient empires such as Egypt, Greece and Rome, but I think it's the vibrant colours, the spiky crown, plus that sort of floaty silk shawl that pushes it further East. Not quite delicate enough to be Hindu, but too vivid for Greco-Roman aesthetics. Or something like that.

I've attached a picture of the famous Greek statue of Nike at Samothrace, or what is left of her, displayed at the Louvre, which, apart from Cleopatra, is the nearest I can get to what Jadis might be like. The statue is headless, & 'armless' which isn't much help, but when it was originally made, like most such old statues, textbooks tell us, it was covered in vivid paint, but which has worn off over the centuries. Yes, the original form of this statue, Nike alighting a ship to bring the good news of Victory, might have well been "dazzlingly beautiful". But surely you would have to go back well before the 636 AD fall of Jerusalem to the Muslim Caliphs to see Jadis as "Persian-esque", especially when the niqabs, abayas, & burqas the women of that region wear, go well back to before the Prophet Mohamed, when the idea for women covering themselves up came from Persian Christians, it would seem. 

Oh, by the way, what would the slaves wear? Just like in 1804 Van Diemen's Land, anything they could get hold of, even if it was animal skins. But then, when it was the slaves who made the beautiful clothes in the Hall of Statues, they might have been able to make clothes for themselves to wear. 

So Tilda Swinton's Jadis costumes had to be one of my favorite, memorable, collection of costume designs of all time. Every single one had some kind of dead animal. I loved her melting crown. It was a well thought-out set of costumes and so HER. I think that Netflix's costume designer is going to be hard pressed to find something I like more. 

I'm going to go a different direction from the suggested Persian designs up above (that's how I envision the Calormene people). I want to see something alien, not inspired by outfits here on earth. And based on the "shameless hussy" comment, I wouldn't be opposed to something with separate pant legs as opposed to a dress or skirt. It gives greater mobility for fighting, riding on top of a carriage through the streets of London, and jumping onto the back of a horse. 

Posted by: @fantasia

I want to see something alien, not inspired by outfits here on earth.

In Marvel's 'The Eternals' they had characters such as the one played by Salma Hayek with a costume which was like an Alien version of ancient Babylon, and the one played by Angelina Jolie which was like an Alien version of ancient Greece 

Do you mean something like that, or completely alien-Alien?

Or in a more outright Alien mannner, perhaps something like Elizabeth Debicki's High Preistess character in Guardians of The Galaxy:

Side note - it probably shows how much Marvel has dominated mainstream fantasy movie making and costume design over the last 15 years!

I am not sure I want exactly Baynes' take on her, but at least for the Charn scenes I want something kind of similar -- tall crown or headdress, lots of flowing elements that would catch wind dramatically, and design motifs involving stylized stars and eyes. Her draped scarf always looked like it was covered in eyes to me -- and it makes thematic sense, the way she plays up how her ancestors could supposedly see into their servants' hearts. 

Inspirations:

• "Madame X" by John Singer Sargent 
• Art Nouveau 
• The frescos and sculptures of Ancient Crete (the Minoans)
• Ancient Egypt 

Fantasia referred above to the "Shameless Hussy " comment. I wonder what costume might shock middle-aged respectable Letty, but not little Polly whose eyes would be no higher than Jadis' waist (rough guess).  What does it reveal? Legs, shoulders, 'upper chest'?  Or is it clingy, revealing every curve?