この茶室の佇まいは格調高雅だ。
The atmosphere of this tea room is dignified and graceful.
上品 is a more common, everyday word for 'refined' or 'elegant', while 格調高雅 is more literary and emphasizes a lofty, classical dignity.
優雅 focuses on graceful beauty and is used broadly, whereas 格調高雅 adds a sense of elevated style and formality.
A four-character compound (yojijukugo) combining 格調 (kakuchō, 'style' or 'tone') and 高雅 (kōga, 'elegance' or 'refinement'). The exact historical derivation is uncertain, but it follows a common pattern of pairing near-synonymous Sino-Japanese morphemes to intensify meaning.