This week, four chemicals stocks are improving their overall rating on Portfolio Grader. Each of these rates an “A” (“strong buy”) or “B” overall (“buy”).

Platform Specialty Products Corp. (PAH) ups its rating to a B (“buy”) this week after earning a C (“hold”) in the week before. In Portfolio Grader’s specific subcategory of Earnings Surprise, PAH also gets an A. For more information, get Portfolio Grader’s complete analysis of PAH stock.

Burcon NutraScience Corporation (BUR) gets a higher grade this week, advancing from a C last week to a B. Burcon NutraScience specializes in nutrition, health and wellness in the field of functional and renewable plant proteins. For more information, get Portfolio Grader’s complete analysis of BUR stock.

Valspar Corporation (VAL) improves from a C to a B rating this week. Valspar is a coating and paint manufacturer and distributor. For more information, get Portfolio Grader’s complete analysis of VAL stock.

Potash Corporation of Saskatchewan Inc.’s (POT) ratings are looking better this week, moving up to a B from last week’s C. Potash Corporation of Saskatchewan produces potash, phosphate, and nitrogen to the agricultural and industrial industries worldwide. For more information, get Portfolio Grader’s complete analysis of POT stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.