The Princess of Wales chose a royal blue Self-Portrait dress for tonight’s Buckingham Palace reception. Below, the Princess with the First Lady of the United States, Dr. Jill Biden, and her granddaughter, Finnegan Biden.
The King greeting guests. 
More about the event from The Telegraph.
[Prince] Albert II and Princess Charlene of Monaco, Queen Letizia of Spain, and Mary, Crown Princess of Denmark, were among the European royals who descended on the Palace for the event.
Some 100 heads of state are set to attend tomorrow’s Coronation, with representatives from 203 countries travelling to London for the big day.
Jill Biden was among the global leaders attending the King’s reception, representing the US delegation on behalf of her husband, President Joe Biden.
I have a mix of photos, including many of the guests as they arrived. From Spain, King Felipe VI and Queen Letizia.
Crown Princess Victoria of Sweden and her father, King Carl Gustaf. 
Crown Prince Haakon of Norway and Crown Princess Mette-Marit.
Princess Beatrix and Princess Catharina-Amalia of the Netherlands. The 19-year-old is a future queen of the Netherlands. 
Abdullah II, the King of Jordan, arrives with his wife, Queen Rania.
King Philippe of Belgium and his daughter, Princess Elisabeth, Duchess of Brabant. The Princess, age 21, is the heir to the Belgian throne.
From Bhutan, King Jigme Khesar Namgyel Wangchuck and Queen Jetsun Pema. 
From Monaco, Prince Albert II and Princess Charlene. 
Kensington Palace released a photo of the Princess and Dr. Biden with Ukraine’s First Lady, Olena Zelenska. 
The King spent time speaking with Ms. Zelenska. 
It was quite a crowd. 
Prince William with Queen Suthida and King Vajiralongkorn of Thailand.
The Princess of Wales with King Jigme and Queen Jetsun Pema of Bhutan. 
The King seemed to be enjoying whatever the President of the European Commission, Ursula von der Leyen (2R), had to say. 
Below, the King greets King Abdullah and Queen Rania from Jordan.
The Duke of Edinburgh greets a guest. Also in this photo, Haakon, Crown Prince of Norway (2nd from left), and in the hot pink dress, Crown Princess Victoria of Sweden.
Princess Anne with the Norwegian royals.
The Princess of Wales welcomes King Felipe of Spain. 
The Princess with King Philippe of Belgium and Princess Elisabeth. 
And King Charles with King Philippe and Princess Elizabeth. You can also see Princess Beatrix and Princess Catharina-Amalia of the Netherlands.
King Felipe and Queen Letizia with the King. 
Crown Princess Mary of Denmark with a curtsey. 
And a greeting for the King. 
In this photo, you also see Crown Prince Frederik. 
Prince Albert and the King. In the background, you can see Grand Duke Henri & Grand Duchess Maria Teresa of Luxembourg.
Now for our look at what Kate wore this evening.
She was in the Self-Portrait Stretch Crepe Twisted Collar Midi Dress ($510), with thanks to UFO No More for the speedy ID. 
The piece is 100% polyester, done in a stretch crepe material. It features a ruched and asymmetrically draped skirt, twisted neckline, puffed sleeves, an invisible back zipper with a keyhole opening, and oversized diamante buttons at the shoulder. It is in stock at Far Fetch ($490), My Theresa ($490), and Self-Portrait ($510). You can see the Princess had a belt made for her dress. . 
The Princess carried her Jenny Packham’ Casa’ clutch. 
She also brought back her Aquazzura Love Link Sling Heels ($1095). Made in blueberry grosgrain, the style features a pointed toe, 4″ heel, and a “heart-shaped chain” at the heel. We first saw her wear the style at last year’s Order of the Garter events. 
The Princess wore the Queen Mother’s Sapphire and Diamond Earrings, first seen when paired with a floral Erdem gown at the 2015 100 Women in Hedge Funds dinner.
More from Her Majesty’s Jewel Chest, referencing The Queen Mother:
…when it came to earrings, she had her favorites and didn’t do much branching out. She did, however, have these earrings, which were rarely worn. They include sapphires surrounded by diamonds with a fringe of diamonds and small sapphires suspended below. Like many pieces in her collection, their history is unknown.
Along with the rest of The Queen Mother’s jewels, we can assume these earrings were inherited by The Queen in 2002. The Queen, who has plenty of sapphire options in her own vault, has never worn them publicly.
We will see you tomorrow, bright and early. Below, I am reposting the TV viewing and streaming info.
NOTE: The Royal Family YouTube Channel will begin its live stream at 7:30am local time, 2:30am ET.
UK COVERAGE:
- BBC coverage begins at 7:30am on BBC One, BBC Two and BBC iPlayer. More details are available here.
- Sky News coverage will begin at 7am (2am ET) and run commercial-free from 9am – 3pm local time. From 5pm – 10pm, special coverage of the Coronation will air on Sky News. A livestream will also be available via Sky’s YouTube and on the Sky News website. There is more detail here.
- ITV starts its coverage at 6am on Saturday.
USA COVERAGE:
- ABC News will have live coverage starting at 5am ET with Michael Strahan as the primary anchor. You can watch streaming coverage at ABC News Live and ABC News Live Replay airs from 10 am to 3 pm ET (7 am to 12 pm PT). Read more details here.
- CBS News coverage begins at 5am on air. You can also watch on CBS News.com and on your mobile or streaming device.
- CNN International will start its live coverage at 1 am ET.
- CNN’s coverage will be anchored by Anderson Cooper starting at 5am and running until noon. It will also be streamed on CNN Live.
- Fox News begins its coverage at 5am with Martha MacCallum anchoring coverage. A streaming link will also be made available on this page. See more info here.
- MSNBC will start its live coverage at 5am.
- NBC News coverages will be anchored by Savannah Guthrie beginning at 5am. You can also watch at TODAY.com and NBCNews.com.
- PBS will carry the BBC’s live uninterrupted coverage of the Coronation from 2:30am-10am ET.
- BBC America shows live coverage of the Coronation beginning at 6am.
CANADA COVERAGE:
- The CBC starts its coverage at 4am. Streaming coverage is available via CBC Gem, CBC News Explore, and CBC Listen. (More info here.)
- CTV’s starts its coverage at 4am, airing across CTV, CP24, CTV News Channel, CTVNews.ca, and the CTV and CTV News apps. (More info here.)
LIVESTREAMS:
- Entities offering live streams include USA TODAY, The New York Times, Paramount+, DirecTV, Hulu + Live TV, Sling TV, Fubo TV, Sky News YouTube channel, BBC, Britbox by BBC and iTV.
And here is the event timing information.
I’ll leave you with this video posted by the Royal Family.
Westminster Abbey is ready for the #Coronation of King Charles III and Queen Camilla. pic.twitter.com/LfS3wJBK4k
— The Royal Family (@RoyalFamily) May 5, 2023
Tess
Monday 8th of May 2023
My immediate thought was - wow, 1980's flashback. In the 80s I was 17-27 and had several dresses like this just with larger shoulder pads. The colour is great and I love the earings, the shoes, and the side-part hair style, but yikes on the dress. I agree that the dress code for this event left me confused. Princess Charlene was in a formal gown and Princess Catharine-Amalia in trousers. I was very glad to see the very young crown princesses in attendance. It can only be a good thing for them to build relationships with King Charles and Prince William in advance of eventually becoming Queens in their own countries. Love the look on Queen Letezia's face as she looks at her husband (picture above Crown Princess Mary curseying).
Ava
Sunday 7th of May 2023
I love the shoes and earrings, and the colour of the dress, but the dress design is very matronly for someone so young. The high neck and shoulder buttons are quite frumpy. At least there isn't a pussy-cat bow too!
QueenMab
Sunday 7th of May 2023
I’m surprised at the lack of love from the majority of people! I agree it has a wee bit too much going on but overall it’s pretty good! Imagine it with a sleek, straight bottom, no slit and no ruching at the hip and it would be my favourite kind of dress—simple with just a little something going on to make it interesting.
Margaret
Saturday 6th of May 2023
What a let-down after the wonderful afternoon look! As someone else mentioned on Facebook, this looks like 80s gone bad. There is just too much fabric and twisting. I do believe Kate was trying to tone down her look so as to not draw attention to herself. I couldn't help thinking that if she had worn Queen Letizia's tea-green Victoria Beckham dress, all the coverage of the evening would feature photos of Kate.
ElizaMo
Saturday 6th of May 2023
This is such a pretty colour on the Princess and she looks very well in it. I quite enjoy the crossover effect on the bodice as brings the neckline up high in a ladylike regal manner. I find the rest of the Self Portrait styling more problematic, particularly as we don't have a wide range of pictures.
While the bodice works well enough, the sleeves are quite high at the shoulder making Catherine look wider at that point where she is already a little broad. She does seem fond of long sleeves gathered into the shoulder and a generous, buttoned cuff.
With only one full length view from the front, I find it hard to tell how tell the skirt works to balance out the wider top. In the picture with Dr Biden and Olena Zelenska the skirt appears to tail way to a narrow point at the knees, although it's just possible that the folded wrap-over feature across the hip might add a useful touch of bulk. I also think that photo might have been taken at an angle which emphasises the unbalanced look. I think the dress may be a sophisticated style concept which could be challenging to pull off at the Self Portrait price point.
It's the earrings which pull off a success for the outfit, those Sapphire and Diamond drop earrings are fabulous royal bling and Catherine has showcased them very effectively with her swept over hairstyle. I'm delighted to see the Aquazzura Love Link Sling Heels return in a more appropriate setting than church, I feel they are quite at home in the cocktail hour. The silver Casa clutch is perfect to chime with the studded slingback.