The overall ratings of four Metals and Mining stocks are down on Portfolio Grader this week. Each of these rates a “D” (“sell”) or “F” overall (“strong sell”).

This week, Mountain Province Diamonds (AMEX:MDM) falls to a D (“sell”), worse than last week’s grade of C (“hold”). Mountain Province Diamonds explores and develops diamond properties. In Portfolio Grader’s specific subcategories of Earnings Revisions and Equity, MDM also gets F’s. To get an in-depth look at MDM, get Portfolio Grader’s complete analysis of MDM stock.

Carpenter Technology‘s (NYSE:CRS) rating weakens this week, dropping to a D versus last week’s C. Carpenter Technology makes and distributes specialty metals and alloys. For more information, get Portfolio Grader’s complete analysis of CRS stock.

Commercial Metals (NYSE:CMC) earns a D this week, falling from last week’s grade of C. Commercial Metals recycles, manufactures, and markets steel and metal products and other related materials. The stock gets F’s in Earnings Revisions and Earnings Surprise. The stock currently has a trailing PE Ratio of 26.2. To get an in-depth look at CMC, get Portfolio Grader’s complete analysis of CMC stock.

The rating of Rubicon Minerals (AMEX:RBY) declines this week from a C to a D. Rubicon Minerals explores for gold deposits in the Red Lake gold camp of Canada, as well as Nevada and Alaska. The stock gets F’s in Equity and Cash Flow. For a full analysis of RBY stock, visit Portfolio Grader.

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.