Exhibit 3.1

AMENDED AND RESTATED

CERTIFICATE OF INCORPORATION

OF

SMITH INTERNATIONAL, INC.

This Amended and Restated Certificate of Incorporation is being filed pursuant to Sections 245 and 242 of the General Corporation Law of the State of Delaware.

FIRST: The name of the corporation is Smith International, Inc. (the “Corporation”).

SECOND: The address of the Corporation’s registered office in the State of Delaware is Corporation Trust Center, 1209 Orange Street in the City of Wilmington, County of New Castle, 19801. The name of the Corporation’s registered agent at that address is The Corporation Trust Company.

THIRD: The purpose of the Corporation is to engage in any lawful act or activity for which corporations may be organized under the General Corporation Law of the State of Delaware or any successor statute (the “DGCL”).

FOURTH: The total number of shares of stock which the Corporation shall have authority to issue is 2,000,000 shares, all such shares being of one class of common stock with a par value of $1.00 per share.

FIFTH: In furtherance of, and not in limitation of, the powers conferred by statute, the Board of Directors is expressly authorized to make, adopt, amend, alter and repeal the bylaws of the Corporation, without any action on the part of the stockholders, except as may otherwise be provided by applicable law or the bylaws of the Corporation.

SIXTH: No director of the Corporation shall be personally liable to the Corporation or any of its stockholders for monetary damages for breach of fiduciary duty as a director to the fullest extent permitted by the DGCL as it now exists or as it may hereafter be amended. Any repeal or modification of this Article Sixth by the stockholders of the Corporation shall be prospective only, and shall not adversely affect any limitation on the personal liability of a director of the Corporation existing at the time of such repeal or modification.

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SEVENTH: (1) Each person who was or is made a party or is threatened to be made a party to or is involved in any action, suit or proceeding, whether civil, criminal, administrative or investigative (hereinafter a “proceeding”), by reason of the fact that he or she or a person of whom he or she is the legal representative is or was a director, officer or employee of the Corporation or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation or of a partnership, joint venture, trust or other enterprise, including service with respect to employee benefit plans, whether the basis of such proceeding is alleged action in an official capacity as a director, officer, employee or agent or in any other capacity while serving as a director, officer, employee or agent, shall be indemnified and held harmless by the Corporation to the fullest extent authorized by the DGCL as the same exists or may hereafter be amended (but, in the case of any such amendment, only to the extent that such amendment permits the Corporation to provide broader indemnification rights than said law permitted the Corporation to provide prior to such amendment), against all expense, liability and loss (including attorneys’ fees, judgments, fines, ERISA excise taxes or penalties and amounts paid or to be paid in settlement) reasonably incurred or suffered by such person in connection therewith and such indemnification shall continue as to a person who has ceased to be a director, officer, employee or agent and shall inure to the benefit of his or her heirs, executors and administrators; provided, however, that except as provided in paragraph (2) of this Article SEVENTH with respect to proceedings seeking to enforce rights to indemnification, the Corporation shall indemnify any such person seeking indemnification in connection with a proceeding (or part thereof) initiated by such person only if such proceeding (or part thereof) was authorized by the Board of Directors of the Corporation. The right to indemnification conferred in this Article SEVENTH shall be a contract right and shall include the right to be paid by the Corporation the expenses incurred in defending any such proceeding in advance of its final disposition; provided, however, that if the DGCL requires, the payment of such expenses incurred by a director or officer in his or her capacity as a director or officer (and not in any other capacity in which service was or is rendered by such person while a director or officer, including without limitation, service to an employee benefit plan) in advance of the final disposition of a proceeding, shall be made only upon delivery to the Corporation of an undertaking by or on behalf of such director or officer, to repay all amounts so advanced if it shall ultimately be determined that such director or officer is not entitled to be indemnified under this Article SEVENTH or otherwise.

(2) If a claim under paragraph (1) of this Article SEVENTH is not paid in full by the Corporation within thirty days after a written claim has been received by the Corporation, the claimant may at any time thereafter bring suit against the Corporation to recover the unpaid amount of the claim and, if successful in whole or in part, the claimant shall be entitled to be paid also the expense of prosecuting such claim. It shall be a defense to any such action (other than an action brought to enforce a claim for expenses incurred in defending any proceeding in advance of its final disposition where the required undertaking, if any is required, has been tendered to the Corporation) that the claimant has not met the standards of conduct which make it permissible under the DGCL for the Corporation to indemnify the claimant for the amount claimed, but the burden of proving such defense shall be on the Corporation. Neither the failure of the Corporation (including its Board of Directors, independent legal counsel or stockholders) to have made a determination prior to the commencement of such action that indemnification of the claimant is proper in the circumstances because he or she had met the applicable standard of conduct set forth in the DGCL, nor an actual determination by the Corporation (including its Board of Directors, independent legal counsel or stockholders) that the claimant has not met such applicable standard of conduct, shall be a defense to the action or create a presumption that the claimant has not met the applicable standard of conduct.

(3) The right to indemnification and the payment of expenses incurred in defending a proceeding in advance of its final disposition conferred in this Article SEVENTH shall not be exclusive of any other right which any person may have or hereafter acquire under any statute, provision of the Amended and Restated Certificate of Incorporation, By-Law, agreement, vote of stockholders or disinterested directors or otherwise.

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(4) The Corporation may maintain insurance, at its expense, to protect itself, any director, officer, employee or agent of the Corporation or another corporation, partnership, joint venture, trust or other enterprise against any expense, liability or loss, whether or not the Corporation would have the power to indemnify such person against such expense, liability or loss under the DGCL.

(5) The Corporation may, to the extent authorized from time to time by the Board of Directors, grant rights to indemnification, and rights to be paid by the Corporation the expenses incurred in defending any proceeding in advance of its final disposition, to any agent of the Corporation to the fullest extent of the provisions of this Article SEVENTH with respect to the indemnification and advancement of expenses of directors, officers and employees of the Corporation.

EIGHTH: The Corporation expressly elects not to be governed by Section 203 of the DGCL, as the same exists or hereafter may be amended.

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