While the proven Zacks Rank places an emphasis on earnings estimates and estimate revisions to find strong stocks, we also know that investors tend to develop their own individual strategies. With this in mind, we are always looking at value, growth, and momentum trends to discover great companies.Of these, perhaps no stock market trend is more popular than value investing, which is a strategy that has proven to be successful in all sorts of market environments. Value investors use a variety of methods, including tried-and-true valuation metrics, to find these stocks.Zacks has developed the innovative Style Scores system to highlight stocks with specific traits. For example, value investors will be interested in stocks with great grades in the "Value" category. When paired with a high Zacks Rank, "A" grades in the Value category are among the strongest value stocks on the market today.One company to watch right now is Polymetal International (AUCOY). AUCOY is currently sporting a Zacks Rank of #2 (Buy), as well as an A grade for Value. The stock holds a P/E ratio of 6.45, while its industry has an average P/E of 9.76. Over the past 52 weeks, AUCOY's Forward P/E has been as high as 10.61 and as low as 6.45, with a median of 8.62.Another notable valuation metric for AUCOY is its P/B ratio of 3.82. The P/B is a method of comparing a stock's market value to its book value, which is defined as total assets minus total liabilities. This company's current P/B looks solid when compared to its industry's average P/B of 4.14. AUCOY's P/B has been as high as 5.88 and as low as 3.82, with a median of 4.89, over the past year.Sibanye Gold Limited (SBSW) may be another strong Mining - Miscellaneous stock to add to your shortlist. SBSW is a # 1 (Strong Buy) stock with a Value grade of A.Additionally, Sibanye Gold Limited has a P/B ratio of 1.57 while its industry's price-to-book ratio sits at 4.14. For SBSW, this valuation metric has been as high as 3.52, as low as 1.41, with a median of 2.15 over the past year.These are just a handful of the figures considered in Polymetal International and Sibanye Gold Limited's great Value grade. Still, they help show that the stock is likely being undervalued at the moment. Add this to the strength of its earnings outlook, and we can clearly see that AUCOY and SBSW is an impressive value stock right now. Zacks’ Top Picks to Cash in on Artificial Intelligence This world-changing technology is projected to generate $100S of billions by 2025. From self-driving cars to consumer data analysis, people are relying on machines more than we ever have before. Now is the time to capitalize on the 4th Industrial Revolution. Zacks’ urgent special report reveals 6 AI picks investors need to know about today.See 6 Artificial Intelligence Stocks With Extreme Upside Potential>>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Polymetal International PLC Sponsored ADR (AUCOY): Free Stock Analysis Report Sibanye Gold Limited (SBSW): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research