The phrase "a stony expression" is correct and usable in written English.
It can be used to describe someone's facial expression that is emotionless or unyielding, often indicating a lack of warmth or friendliness.
Example: "Despite the good news, she maintained a stony expression, revealing nothing of her true feelings."
Alternatives: "a blank expression" or "an impassive face".
Her face hardened into a stony expression I'd seen on her only a handful of times in our career as prospectors.
Australia's bowling coach, Craig McDermott – whose enormously successful tenure has been defined by the three word mantra: pitch it up – wore a stony expression on the Australian team's balcony.
"Wow, incisive commentary there, mate: 'It feels like the game's started, then it got to 40 minutes, then it stopped going, and then it was the end of play.'" In another corner of the bar, Ellen Henrich – described by her friend as a "mad Wallabies nut" – is wearing a stony expression beneath her Día de Muertos facepaint.
Even with television cameras obstructing his vision, Bling wore a stony expression as he walked down the fairways at Pebble Beach.
"No one would want to live in a place like this," she comments with a joyless, stony expression.
Crier is a stolid, businesslike gentleman of sixty-six, withethe stony expression and rumbling voice of one of those tough inner-city high-school principals who show up in Disney movies.
The phone conversation lasted just a few seconds, but Stacy Santiago knew from her husband's stony expression what it meant.
"If someone's able to keep such a stony-faced expression, it's either high theatrics or they have no sympathy," she added.
Some wore football jerseys, some wore hijabs, some wore a cross around their necks, but all wore stony expressions of sombreness.
I took their stony expressions as signs of arrogance, snobbishness, and even hostility.
But at the Armory the transformative power of stardom made their stony expressions look less like stage fright than like deadpan cool — the sang-froid of rock stars content to make you come to them.
