Unpredictability is at its peak this earnings season for investors in precious metals. Where Barrick Gold Corp. (GOLD -2.01%) shares tumbled by double-digit percentages in a day after the gold miner surprisingly missed earnings estimates by a big margin and downgraded its production outlook, a smaller silver miner like Tahoe Resources saw its shares zoom after delivering record earnings and cash flows for its last quarter.

For investors in gold and silver, the roller-coaster ride may not be over yet, what with streaming heavyweights Silver Wheaton Corp. (WPM -1.20%) and Royal Gold Inc. (RGLD -1.17%) set to report their quarterly earnings this week. Will they surprise the markets and continue to outperform traditional miners? Here's what investors can expect to see.

Looking at a graph through a magnifying glass.

Image source: Getty Images

Silver Wheaton: High expectations, but watch this metric

Silver Wheaton, the world's largest precious metals streaming company, will release its first-quarter numbers on May 9 after market close. Expectations have been running high ever since the company reported record production, sales volumes, and revenues for 2016 in March. More notably, Silver Wheaton's gold sales crossed the 100,000 ounces mark for the first time during the fourth quarter, thanks to higher deliveries from Vale's Salobo mine. What investors may have missed, however, was that Silver Wheaton's silver production declined 26% year over year in Q4, so higher gold production is merely offsetting weakness elsewhere.

2017 projected20162015
Silver (in ounces) 28 million 30.4 million 30.7 million
Gold (in ounces) 340,000 353,700 243,000

Data source: Silver Wheaton financials. Table by author.

As you can see, Silver Wheaton's projections for 2017, as they stand now, are pretty dismal. However, part of what led to this muted outlook was an ongoing strike at Primero Mining Corp.'s (PPP) San Dimas mine, which was called off last month. Primero just confirmed that it's striving to resume operations at San Dimas and steer it to profitability. As San Dimas is among Silver Wheaton's top three sources of silver, there's a chance the company could upgrade its production outlook. Investors should keep an eye out for news on that front in Silver Wheaton's upcoming earnings report.

Analysts' expect Silver Wheaton's Q1 earnings to come in nearly 30% higher at $0.13 per share on 14% higher revenues. However, gold prices were weak during the quarter, and Silver Wheaton's production is also on a decline that could weigh on its top line. What really matters to investors, though, is the company's production outlook for 2017 and beyond. If Silver Wheaton upgrades its five-year estimated average silver and gold production of 29 million ounces and 340,000 ounces, respectively, investors could find an excuse to put the stock on their radar especially after its 15% decline in the past three months.

Royal Gold: Could be headed to a record year

Royal Gold follows a July-to-June financial year, so it'll be reporting its fiscal third-quarter numbers on the morning of May 11. Much like Silver Wheaton, expectations from Royal Gold are high after it last reported 55% jump in operating income and record operating cash flows for the six months ended Dec. 31, 2016. If it maintains its growth streak in Q3, it might well be on its way to a record financial year in terms of revenue and cash flows. Analysts' expect to see 16% growth in revenues, and adjusted earnings of $0.35 per share versus $0.29 in the year-ago quarter.

Chart showing Royal Gold's operating cash flows for recent quarters.

Image source: Royal Gold's presentation at the European Gold Forum.

Based on Royal Gold's recent update, quick calculation suggests that it could report 6% to 7% higher year-over-year gold sales at around 58,000 ounces, though it's likely to have realized flattish average prices year over year. But with cost of sales also likely to have improved, I expect Royal Gold to report strong earnings this week, though I think that 16% top-line growth estimate could be a little too optimistic because of a possible decline in deliveries from Barrick's Pueblo Viejo mine, which is also among Royal Gold's primary sources of gold. Barrick reported weaker production from Pueblo Viejo during its Q1 earnings release, citing maintenance as the reason.

It's worth noting, though, that Barrick expects full-year production from Pueblo Viejo to be on track, which also explains why it is so important for investors to look beyond the headlines this week and instead focus on the trend in Royal Gold's production estimates and cash flows for 2017 and beyond. If it's a smooth sail, investors can remain bullish about Royal Gold.