Hey there, /u/usaf2222. There wasn't any "oh, damn" moment, if that's what you're asking. From the perspective of the Russian-American Company, gold was actually a headache.

Russian officials were aware of traces of gold on the Kenai Peninsula as early as the 1840s, when engineer and geologist Peter Petrovich Doroshin arrived in the territory. From April 20 to Sept. 22, 1848, Doroshin, six Russians, two Creoles and four Tlingits prospected the Kenai River in search of placer gold. Apparently, there had been reports of placer gold in the area.

Sources differ about the amount of gold recovered, but in any event, Doroshin returned to New Archangel (Sitka) with the news that the amount of gold was not economically viable for development.

When news of the California Gold Rush arrived in Sitka, Doroshin and his crew sped south to California, arriving in San Francisco in December 1848. After surviving some harrowing encounters with criminals along the Yuba River, they managed to take away nearly 12 pounds of placer gold with their gold pans. They subsequently bought a three-masted ship for the Russian-American Company and returned to Alaska.

Doroshin and his group made repeated attempts at prospecting in the Kenai River basin but never found paying quantities of the mineral. He turned his attention to coal mining and was more successful at that.

In the 1860s, Russian-American Company officials found themselves worried by a stampede to the Stikine River that started when rumors spread in British Columbia that gold had been found there.

This area, on the mainland of the Alaska panhandle, was being leased by the Hudson's Bay company and was not under the direct authority of the RAC at the time, but the fact that it brought hundreds of Americans and Canadians to the area worried the Russians.

There were fewer than 1,000 Russians in Russian America at its peak, and the Stikine River experience showed that even a minor stampede would bring many more Americans and Canadians than that.

Indeed, this lack of control, and the belief that Russia could not hold on to its American possessions in the event of American encroachment, was one of the factors that led to the sale of Russian America. Tsar Alexander's brother, Admiral-General Konstantin, was foremost among those who believed that Russian America could not be kept if American and Canadian settlers moved into the area en masse. Russia did not have the resources or ability to stop them from doing so.

If you'll permit me to engage in speculation, I imagine that if Russia had not sold Alaska, it would have soon lost it, much as Mexico lost Texas and California to encroaching American settlers. This likely would have taken place no later than the 1880s, when the Juneau Gold Rush brought thousands of miners to Southeast Alaska.