SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(a)

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 8)

DGSE COMPANIES, INC.

(Name of Issuer)

Common Stock, $.01 par value per share

(Title of Class of Securities)

395304 10 8

(CUSIP Number)

Carl D. Gum, III

General Counsel

NTR Metals, LLC

10720 Composite Drive

Dallas, TX 75220

(469) 522-1111

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

October 31, 2012

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.    ¨

SCHEDULE 13D

Item 1. Security and Issuer.

This Amendment No. 8 to the Statement on Schedule 13D amends the Statement on Schedule 13D originally filed with the Securities and Exchange Commission on June 1, 2010, which relates to the common stock, $0.01 par value per share (the “Common Shares”), of DGSE Companies, Inc., a Nevada corporation (the “Issuer”), as amended by Amendment No. 1 to the Statement on Schedule 13D filed on April 18, 2011, Amendment No. 2 to the Statement on Schedule 13D filed on June 14, 2011, Amendment No. 3 to the Statement on Schedule 13D filed on August 4, 2011, Amendment No. 4 to the Statement on Schedule 13D filed on August 16, 2011, Amendment No. 5 to the Statement on Schedule 13D filed on September 19, 2011, Amendment No. 6 to the Statement on Schedule 13D filed on October 31, 2011 and Amendment No. 7 to the Statement on Schedule 13D filed on February 14, 2012. The principal executive offices of the Issuer are located at 11311 Reeder Road, Dallas, Texas 75229.

Item 2. Identity and Background.

No material change.

Item 3. Source and Amount of Funds or Other Consideration.

No material change.

Item 4. Purpose of Transaction.

Item 4 is hereby amended to add the following text to the end of the fourth paragraph:

As a result of the exercise of the Option Contract, third-party proxies granting Dr. Smith voting power over 556,976 Common Shares terminated.

Item 4 is hereby amended to add the following paragraph immediately after the fourth paragraph:

On September 9, 2011, the Reporting Person entered into a Stock Agreement (the “Stock Agreement”) with James J. Vierling (“Vierling”) under which the Reporting Person agreed, upon Vierling’s request prior to December 31, 2012 (the “Termination Date”), to transfer to Vierling 375,000 Common Shares owned by the Reporting Person to Vierling in exchange for the assignment and transfer by Vierling to the Reporting Person of 147,000 Common Shares and certain stock options owned by Vierling. On October 31, 2012, the Reporting Person and Vierling entered into an agreement (the “Extension Agreement”) to extend the Termination Date to March 31, 2012; provided, however that, if Vierling exercises his rights under the Stock Agreement and such exercise would result in the Reporting Person being subject to short-swing profit liability, the Reporting Person will have the ability to defer such exercise and extend the exercise period for six months (but not beyond March 31, 2014). The Stock Agreement and the Extension Agreement are incorporated herein by reference and are exhibits to this Statement. Any descriptions in this Statement of the Stock Agreement and the Extension Agreement are qualified in their entirety by reference to the actual text of such document.

Excluding the above amendments, the tenth paragraph of Item 4 is hereby amended and restated in its entirety to read as follows:

Following the Initial Investment, the Reporting Person has purchased, and may continue to purchase, Common Shares in the open market at market prices for the purpose of making additional investments in the Issuer. The Reporting Person intends to continuously review its investment in the Issuer, including possible additional acquisitions of Common Shares, and may in the future change its present course of action. The Reporting Person, from time to time, engages in commercial transactions with the Issuer in the regular course of business. Following the completion of the transactions described herein, the Reporting Person expects to continue to engage in such commercial transactions. The Reporting Person is currently evaluating the identification and nomination of qualified, independent individuals to serve on the Issuer’s board of directors. The Reporting Person and the Issuer may also engage in more significant transactions that may not be in either party’s regular course of business.

Item 5. Interest in Securities of the Issuer.

No material change.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Item 6 is hereby amended and restated in its entirety to read as follows:

See Item 4 for a description of the Partial Assignment Agreement, the Closing Agreement, the NTR Irrevocable Proxy, the Lock-Up Agreement, the Option Contract, the Escrow Agreement, the Agreement to Exercise Rights, the Agreement to Execute Smith Irrevocable Proxy, the Smith Irrevocable Proxy, the Merger Agreement, the Securities Purchase Agreement, the Merger Registration Rights Agreement, the Purchase Registration Rights Agreement, the Merger Lock-Up Agreement, the Merger Escrow Agreement, the Debt Cancellation Agreement, the Option Grant Agreement, the Debt Forgiveness Letter Agreement, the Exercise Agreement, as amended, the Escrow Agreement, as amended, the Stock Agreement and the Extension Agreement.

Item 7. Materials to be Filed as Exhibits.

Item 7 is amended and restated in its entirety to read as follows:

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: October 31, 2012

EXHIBIT INDEX

Exhibit 99.24

STOCK AGREEMENT

This Stock Agreement (“Agreement”) is made and entered into as of September 9, 2011, by and between NTR Metals, LLC, a Texas limited liability company (“NTR”) and James J. Vierling (“Vierling”).

R E C I T A L S:

WHEREAS, NTR and Vierling are or will shortly become parties to that certain Agreement and Plan of Merger Among DGSE Companies, Inc. (“DGSE”), SBT, Inc., Southern Bullion Trading, LLC (“SBT”), NTR Metals, LLC and Members of Southern Bullion Trading, LLC dated as of September 12, 2011 (“Merger Agreement”) whereby SBT will merge with and into SBT, Inc.; and

WHEREAS, pursuant to the Merger Agreement, Vierling will receive 147,000 shares (24.5% of 600,000) of DGSE common stock, par value $0.01 per share (the “Vierling Merger Stock”); and

WHEREAS, pursuant to the Merger Agreement and the associated DGSE Companies Inc. Option Grant Agreement (“Option Agreement”, attached to the Merger Agreement as Exhibit F), one or more members of the SBT, Inc. management, including Vierling, may, at the discretion of NTR and if certain conditions are met, receive options to acquire up to an aggregate of 500,000 shares of DGSE common stock, par value $0.01 per share (the “Option Stock”); and

WHEREAS, NTR wishes to guarantee to Vierling that if the merger of SBT into SBT, Inc. is consummated, then Vierling will receive from or on behalf of NTR, at no cost to Vierling, 375,000 shares of unrestricted DGSE stock, par value $0.01 per share (“Guarantee Stock”), and Vierling wishes, in return, to assign and transfer to NTR to the full extent permissible by law all of the Vierling Merger Stock and all of the Option Stock received by Vierling.

NOW, THEREFORE, in consideration of the mutual premises, representations, warranties and conditions set forth in this Agreement, the parties hereto, intending to be legally bound, hereby agree as follows:

1. NTR agrees that if the merger of SBT into SBT, Inc. is consummated, then for period beginning at said consummation and continuing thereafter through and including December 31, 2012, Vierling shall have the right to request and thereafter receive within 60 days from or on behalf of NTR, at no cost to Vierling, 375,000 shares of Guarantee Stock;

2. Vierling agrees that in exchange for and upon receipt of the 375,000 shares of Guarantee Stock, Vierling will assign and transfer to NTR – to the extent and in a manner not inconsistent with the Merger Agreement and other closing documents relating thereto - all of the Vierling Merger Stock and all of the Option Stock received by Vierling.

3. To the extent not paid by SBT, NTR agrees to pay all income taxes owed by Vierling as a result of SBT profits earned from January 1, 2011 until the day the merger of SBT into SBT, Inc. is closed.

4. If the merger of SBT into SBT, Inc. is not closed by December 31, 2011, or if Vierling fails to request the Guarantee Stock by December 31, 2012, then all parties shall be released from all of their respective obligations hereunder.

[SIGNATURE PAGE FOLLOWS]

IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the date first written hereinabove.

2

Exhibit 99.25

NTR METALS, LLC

AMENDMENT TO STOCK AGREEMENT

October 31, 2012

This Amendment to Stock Agreement (this “Agreement”) is made and entered into as of the date set forth above, by and among NTR Metals, LLC (the “Company”) and James J. Vierling (“Vierling”). Capitalized terms used but not defined herein have the meaning assigned to them in the Stock Agreement (as defined below).

RECITALS

WHEREAS, the undersigned entered into that certain Stock Agreement, dated as of September 9, 2011, by and between the Company and Vierling (the “Stock Agreement”), pursuant to which the Company agreed, upon Vierling’s request prior to December 31, 2012, to transfer to Vierling 375,000 shares of Guarantee Stock in exchange for the assignment and transfer by Vierling to the Company of (a) the 147,000 shares of Vierling Merger Stock and (b) any Option Stock received by Vierling;

WHEREAS, the Stock Agreement has not been exercised by Vierling and remains in effect; and

WHEREAS, pursuant to this Agreement, Vierling and the Company are amending the terms of the Stock Agreement.

NOW, THEREFORE, in consideration of the foregoing and the mutual covenants and agreements herein contained, and intending to be legally bound hereby, the parties hereto agree as follows:

AGREEMENT

1. Extension. Section 1 of the Stock Agreement is hereby amended so that the reference to “December 31, 2012” is changed to “March 31, 2013”.

2. Further Extensions. The parties agree that the Stock Agreement, as amended, may not be exercised if, upon Vierling’s request to exercise, the Company informs Vierling that such exercise may reasonably result in the Company being subject to short-swing profit liability under Section 16(b) of the Securities Exchange Act of 1934 (herein referred to as an “Exercise-deferral Notice”). In the event of any such Exercise-deferral Notice under this Agreement, the parties agree that the exercise period of the Stock Agreement will be extended for a period of six months, provided that no extension will defer the exercise period beyond March 31, 2014.

3. Authority. Each party hereto represents and warrants that it had and has all necessary authority and legal capacity to enter into the Stock Agreement and this Agreement.

4. Taxes. All taxes associated with the Stock Agreement and this Agreement shall be borne by Vierling. Vierling acknowledges that (a) he has had the opportunity to consult with his own tax, legal and accounting advisors with respect to the Stock Agreement and this Agreement and (b) the Company has made no representations or warranties with respect to the tax, legal or accounting consequences of the Stock Agreement or this Agreement.

5. Choice of Law. The Stock Agreement and this Agreement are to be construed according to the laws of the State of Texas.

6. Integration of Contract. The Stock Agreement as amended by this Agreement constitutes the full understanding of the parties, and no terms, conditions, understandings or agreements purporting to modify or vary the terms of the Stock Agreement or this Agreement shall be binding unless hereafter made in writing and signed by the party to be bound.

7. Counterparts. This Agreement may be executed in one or more counterparts, each of which will be deemed an original, but all of which together will constitute one and the same instrument.

[Signature page follows]

IN WITNESS HEREOF, the undersigned have executed this Agreement on the date first appearing above.