The phrase "a small ray of" is correct and usable in written English.
It can be used to convey a sense of hope or positivity in a situation that may otherwise seem bleak or negative.
Example: "Even in the darkest times, she found a small ray of hope that kept her going."
Alternatives: "a glimmer of" or "a hint of".
Then one day "a small ray of light broke in upon my gloom.
January is the time of year when, for us gardeners, a small ray of hope breaks through the grey skies.
Reading about the newly formed American Majority Institute was like a small ray of light in a blighted landscape.
But a small ray of sun reached the cliff itself, heating that spot up to 50 degrees Celsius — the temperature of Death Valley in high summer.
"In the horrifying story of his treatment, a small ray of light is that he was not abandoned by all of his colleagues at GCHQ.
The NCS is a small ray of sunshine in a very gloomy picture at the moment – it's not a replacement for focused youth services," he says.
And it's a very small ray of sunshine that they might now have that education, though for the moment they're still at the village school.
The whole thing is encased in an elastomeric sheath very much in the shape of a small ray.
"What a life he has led," exulted Morgan Forster, who himself lived past ninety, "and how he has led it!" When he was still at work on "After the Deluge," Leonard Woolf suggested that "even a failure might bring some small ray of light or grain of knowledge," but it was on the last page of the last volume of his memoirs that he could say with sincerity, "There are other assets of old age.
One small ray of hope: studies of T-20, a member of a new class of drugs known as fusion inhibitors, showed the experimental drug held promise for those in whom the AIDS virus has developed resistance to standard drugs.
That's one small ray of hope in an otherwise hair-raising read.
