Investors interested in stocks from the Chemical - Diversified sector have probably already heard of Huntsman (HUN) and Albemarle (ALB). But which of these two companies is the best option for those looking for undervalued stocks? Let's take a closer look.There are plenty of strategies for discovering value stocks, but we have found that pairing a strong Zacks Rank with an impressive grade in the Value category of our Style Scores system produces the best returns. The Zacks Rank favors stocks with strong earnings estimate revision trends, and our Style Scores highlight companies with specific traits.Huntsman has a Zacks Rank of #2 (Buy), while Albemarle has a Zacks Rank of #3 (Hold) right now. This means that HUN's earnings estimate revision activity has been more impressive, so investors should feel comfortable with its improving analyst outlook. But this is only part of the picture for value investors.Value investors also try to analyze a wide range of traditional figures and metrics to help determine whether a company is undervalued at its current share price levels.Our Value category grades stocks based on a number of key metrics, including the tried-and-true P/E ratio, the P/S ratio, earnings yield, and cash flow per share, as well as a variety of other fundamentals that value investors frequently use.HUN currently has a forward P/E ratio of 13.44, while ALB has a forward P/E of 39.94. We also note that HUN has a PEG ratio of 1.52. This figure is similar to the commonly-used P/E ratio, with the PEG ratio also factoring in a company's expected earnings growth rate. ALB currently has a PEG ratio of 3.64.Another notable valuation metric for HUN is its P/B ratio of 1.71. Investors use the P/B ratio to look at a stock's market value versus its book value, which is defined as total assets minus total liabilities. By comparison, ALB has a P/B of 4.08.These metrics, and several others, help HUN earn a Value grade of B, while ALB has been given a Value grade of D.HUN stands above ALB thanks to its solid earnings outlook, and based on these valuation figures, we also feel that HUN is the superior value option right now.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 Huntsman Corporation (HUN): Free Stock Analysis Report Albemarle Corporation (ALB): Get Free Report To read this article on Zacks.com click here. Zacks Investment Research