The phrase "although beautiful" is correct and usable in written English.
You can use it to introduce contrast in the meaning of a sentence. For example, "The city was overcrowded and chaotic, although beautiful."
Although beautiful beyond compare, it was her inner beauty that shone brightest.
Although beautiful, it had been hard to take at times.
The abbreviated chapters, although beautiful vignettes, don't always cohere.
The show is not spectacular, exactly, although beautiful art is beautiful art.
The Frick show, by way of the National Gallery of Canada, is not spectacular, exactly, although beautiful art is beautiful art and always a privilege to see.
Watson instinctively gets that the fairways-to-greens march to excellence, although beautiful to behold, is a bit intimidating to the average fan, who looks upon such perfection as unattainable.
The painting, although startlingly beautiful in its velvety, deep-viridian play of light and shadow, makes us uneasy.
Autumn in Paris, although very beautiful, might give a note of sadness or melancholy that we shall try to keep out of this story.
In the end, it wasn't the punters day although the beautiful Cyfor Malta was almost backed down to favouritism when winning the ladbrokes.com Handicap Chase at 3-1.
Although breathtakingly beautiful, Olu Deniz's seafront is very commercialised these days – there are full-English-breakfast joints galore and the skies are jostling with paragliders scattered like DayGlo Smarties across the blue.
There is also no prospect of it being cleaned in the forseeable future, meaning crowds view a work whichthat, although undeniably beautiful, has several layers of old, cracked varnish.
