DRII Diamond Resorts International, Inc.

This statement relates to the common stock, par value $0.01 per share (the “Common Stock”), of Diamond Resorts International, Inc. (the “Issuer”). The address of the principal executive offices of the Issuer is 10600 West Charleston Boulevard, Las Vegas, Nevada 89135.

This statement is being filed by 1818 Partners, LLC, a Nevada limited liability company (the “Reporting Person”).

The principal business address of the Reporting Person is 10600 West Charleston Boulevard, Las Vegas, NV 89135.

The Reporting Person is primarily engaged in the business of holding securities of the Issuer.

Schedule A hereto sets forth information regarding persons referred to in Instruction C to Schedule 13D.

The Reporting Person has not, during the past five years, nor, to the best of the Reporting Person’s knowledge, have any of the persons listed on Schedule A hereto (i) been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

The Reporting Person is deemed to be a member of a “group,” as such term is defined in Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and Rule 13d-5 promulgated thereunder, as a result of being party to the Stockholders Agreement (as defined herein), as more fully described in Items 4 and 5 hereof.

On July 24, 2013, the Issuer closed the initial public offering (the “IPO”) of an aggregate of 17,825,000 shares of Common Stock at the IPO price of $14.00 per share. In the IPO, the Issuer sold 16,100,000 shares of Common Stock, and Cloobeck Diamond Parent, LLC (“CDP”), in its capacity as a selling stockholder, sold 1,725,000 shares of Common Stock.

Pursuant to an Exchange Agreement, dated as of July 17, 2013 (the “Exchange Agreement”), by and among the Issuer, Diamond Resorts Parent, LLC (“Diamond LLC”) and the members of Diamond LLC party thereto, in connection with, and immediately prior to the closing of, the IPO, (i) the holders of Class A common units of Diamond LLC contributed all of their Class A common units of Diamond LLC to the Issuer in return for an aggregate of 53,697,402 shares of Common Stock, and (ii) the holders of Class B common units of Diamond LLC contributed all of their Class B common units of Diamond LLC to the Issuer in return for an aggregate of 360,465 shares of Common Stock (collectively, the “Exchange”). Immediately following the consummation of the Exchange, Diamond LLC was merged with and into the Issuer, with the Issuer remaining as the surviving entity.

In connection with the closing of the IPO, existing call options held by the Reporting Person representing the right to purchase Class A common units in Diamond LLC were converted, pursuant to the terms of such call options, into call options to purchase (i) 4,535,426 shares of Common Stock from DRP Holdco, LLC (the “DRPH Call Option”) and (ii) 431,875 shares of Common Stock from Silver Rock Financial LLC and other entities affiliated therewith (the “Silver Rock Call Option” and, together with the DRPH Call Option, the “Call Options”).

The summaries contained herein of the Exchange Agreement, the DRPH Call Option and the Silver Rock Call Option do not purport to be complete and are qualified in their entirety by reference to the full text of such documents, which are filed as Exhibits 1, 2 and 3, respectively, to this Schedule 13D and are incorporated herein by reference.

The disclosure set forth in Item 3 of this Schedule 13D is incorporated herein by reference.

In connection with the closing of the IPO, the Reporting Person has entered into a Stockholders’ Agreement, dated as of July 17, 2013 (the “Stockholders Agreement”), with other individuals and entities who are now stockholders of the Issuer. The Stockholders Agreement covers an aggregate of 40,119,261 shares of Common Stock, representing approximately 53.2% of the outstanding Common Stock. In addition, CDP and DRP Holdco, LLC (“DRPH”), which beneficially own an aggregate of approximately 22.0% and 15.0%, respectively, of the Common Stock, and are parties to the Stockholders Agreement, entered into a Director Designation Agreement, dated as of July 17, 2013 (the “Director Designation Agreement”), with the Issuer.

Pursuant to the Director Designation Agreement, (i) CDP has the right to designate up to two of the Issuer’s directors, for so long as CDP and its affiliates, collectively, own at least ten percent (10%) of the issued and outstanding shares of Common Stock, and (ii) DRPH has the right to designate up to two of the Issuer’s directors, for so long as DRPH and its affiliates, collectively, own at least ten percent (10%) of the issued and outstanding shares of Common Stock, provided that, in each case, if the board of directors of the Issuer (the “Board”) determines in good faith, after consultation with outside legal counsel, that the nomination of any such designee would constitute a breach of its fiduciary duties to the Issuer’s stockholders, CDP or DRPH, as applicable, must designate another individual (who will also be subject to the same determination by the Board).

Pursuant to the Stockholders Agreement, each of the parties thereto has agreed to cause the shares of Common Stock held by such party to be voted, at any meeting of stockholders of the Issuer called for such purpose, for the individuals nominated by the Board for election to the Board (including those nominees selected by CDP and DRPH pursuant to the Director Designation Agreement). Each of the parties to the Stockholders Agreement has agreed to appoint Stephen J. Cloobeck and David F. Palmer as their proxies and attorneys-in-fact to vote their shares of Common Stock in the event that they fail to vote in accordance with the provisions of the Stockholders Agreement. In addition, in the event that any party to the Stockholders Agreement transfers any shares of Common Stock to an affiliate, another party to the Stockholders Agreement or an affiliate of another party to the Stockholders Agreement, the transferee will be required to sign a joinder to the Stockholders Agreement.

As a result of the Stockholders Agreement, the parties thereto are deemed to constitute a “group,” for purposes of the Exchange Act, that holds more than 50% of the Common Stock, and the Issuer will therefore qualify as a “controlled company” under the corporate governance rules of the New York Stock Exchange.

In connection with the closing of the IPO, (i) certain parties to the Stockholders Agreement purchased shares of Common Stock in the IPO pursuant to the directed share

program established by the underwriters for the IPO, (ii) each member of the Board who is not an officer or employee of the Issuer, or the Chairman or Vice Chairman of the Board (each such individual, a “Non-Officer Director”) was granted shares of restricted common stock for service on the Board, pursuant to the Issuer’s 2013 Incentive Compensation Plan, and (iii) each Non-Officer Director received shares of fully vested Common Stock in lieu of the cash retainer to which such Non-Officer Director was otherwise entitled, pursuant to the Non-Officer Director Share Accumulation Program adopted as part of the Issuer’s 2013 Incentive Compensation Plan. Pursuant to the Non-Officer Director Share Accumulation Program, each Non-Officer Director is entitled to elect to utilize all or a portion of his annual retainer fee to acquire shares of Common Stock.

The transactions contemplated by the Stockholders Agreement and the Director Designation Agreement may result in certain actions specified in Items 4(a) through (j) of Schedule 13D, including changes in the Board. Furthermore, as a stockholder of the Issuer, on an ongoing basis, the Reporting Person will review the Issuer’s operating, management, business affairs, capital needs and general industry and economic conditions, and, based on such review, the Reporting Person may, from time to time, determine to increase or decrease its ownership of Common Stock, vote to approve an extraordinary corporate transaction with regard to the Issuer or engage in any of the events set forth in Items 4(a) through (j) of Schedule 13D. Except as otherwise provided herein, the Reporting Person currently has no intention of engaging in any of the events set forth in Items 4(a) through (j) of Schedule 13D.

The summaries contained herein of the Stockholders Agreement and the Director Designation Agreement do not purport to be complete and are qualified in their entirety by reference to the full text of such documents, which are included as Exhibits 4 and 5, respectively, to this Schedule 13D and are incorporated herein by reference.

(a) The Reporting Person may be deemed to beneficially own 4,967,301 shares of Common Stock, representing approximately 6.58% of the Issuer’s outstanding Common Stock (based on 75,447,688 shares of Common Stock outstanding).

(b) The Reporting Person has shared voting power and shared dispositive power with regard to the 4,967,301 shares of Common Stock underlying the Call Options held by it.

The share ownership reported for the Reporting Person does not include any shares of Common Stock owned by the other parties to the Stockholders Agreement, except to the extent disclosed in this Schedule 13D. The Reporting Person is deemed to be a member of a “group” for purposes of the Exchange Act with the other parties to the Stockholders Agreement. The Reporting Person disclaims beneficial ownership of any shares of Common Stock owned by the other parties to the Stockholders Agreement, except to the extent disclosed in this Schedule 13D.

(c) No transactions in the Common Stock have been effected by the Reporting Person within the past 60 days, except as disclosed under Item 3 of this Schedule 13D, all of which disclosures are incorporated herein by reference.

(d) With respect to the 4,535,426 shares of Common Stock underlying the DRPH Call Option held by the Reporting Person, DRPH currently has the power to direct the receipt of dividends from such shares of Common Stock. With respect to the 431,875 shares of Common Stock underlying the Silver Rock Call Option, Silver Rock

Financial LLC and other entities affiliated therewith have the power to direct the receipt of dividends from such shares of Common Stock. Upon exercise of the Call Options by the Reporting Person, Praesumo Partners, LLC, Cloobeck Companies, LLC and Chautauqua Management, LLC, the managing members of the Reporting Person, will share the power to direct the receipt of dividends from, or the proceeds from the sale of, the underlying shares of Common Stock.

(e) Not applicable.

The responses set forth in Items 3 and 4 of this Schedule 13D are hereby incorporated by reference.

Each of the Issuer’s officers, directors and principal stockholders (including the Reporting Person) has executed a Lock-Up Agreement (each, a “Lock-Up Agreement” and, collectively, the “Lock-Up Agreements”). Each of the Lock-Up Agreements provides that the party thereto will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any shares of Common Stock or securities convertible into or exchangeable or exercisable for any shares of Common Stock, enter into a transaction that would have the same effect, or enter into any swap, hedge or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of Common Stock, or publicly disclose the intention to make any offer, sale, pledge or disposition, or to enter into any transaction, swap, hedge or other arrangement, without, in each case, the prior written consent of Credit Suisse Securities (USA) LLC, for a period of 180 days after July 18, 2013 (which 180-day period is subject to extension under certain specified conditions).

The Reporting Person is party to that certain Second Amended and Restated Registration Rights Agreement, dated as of July 21, 2011 (the “Registration Rights Agreement”). Pursuant to the Registration Rights Agreement, the Issuer has agreed to provide to DRPH, stockholders related to Wellington Management Company, LLP and stockholders related to Silver Rock Financial LLC (collectively, the “Demand Rights Investors”) certain demand registration rights that entitle the Demand Rights Investors (subject to certain minimum thresholds for ownership of Common Stock, limitations on the number of demand registrations that can be requested and customary cutbacks) to require that the Issuer register all or part of the shares of Common Stock held by the Demand Rights Investors. In addition, pursuant to the Registration Rights Agreement, the Issuer has agreed to provide to the parties thereto, including the Reporting Person, certain piggyback registration rights with respect to the Common Stock, subject to customary cutbacks.

Descriptions and summaries of the Lock-Up Agreements and the Registration Rights Agreement set forth above in this Item 6 do not purport to be complete and are qualified in their entirety by reference to the full text of such documents, which are included as Exhibits 6 and 7, respectively, to this Schedule 13D and are incorporated herein by reference.

The following documents are filed as exhibits:

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: August 5, 2013

Schedule A

Managing Members of 1818 Partners, LLC

The managing members of 1818 Partners, LLC are Chautauqua Management, LLC, a Nevada limited liability company, Cloobeck Companies, LLC, a Nevada limited liability company, and Praesumo Partners, LLC, an Illinois limited liability company.

The address of the principal business and/or principal office of Chautauqua Management, LLC is 10600 West Charleston Boulevard, Las Vegas, NV 89135. Chautauqua Management, LLC is primarily engaged in the business of investing in securities and providing consulting and managing services.

The address of the principal business and/or principal office of Cloobeck Companies, LLC is 10600 West Charleston Boulevard, Las Vegas, NV 89135. Cloobeck Companies, LLC is primarily engaged in the business of investing in securities.

The address of the principal business and/or principal office of Praesumo Partners, LLC is 1 N. Wacker Drive, 48th Floor, Chicago, IL 60606. Praesumo Partners, LLC is primarily engaged in the business of identifying, brokering and investing in sales, restructuring, investment and other transactions.

Sole Manager of Chautauqua Management, LLC

The sole manager of Chautauqua Management, LLC is David F. Palmer, a United States citizen. The address of the principal business and/or principal office of Mr. Palmer is 10600 West Charleston Boulevard, Las Vegas, NV 89135. Mr. Palmer’s principal occupation or employment is serving as President and Chief Executive Officer of the Issuer.

Sole Manager of Cloobeck Companies, LLC

The sole manager of Cloobeck Companies, LLC is Stephen J. Cloobeck, a United States citizen. The address of the principal business and/or principal office of Mr. Cloobeck is 10600 West Charleston Boulevard, Las Vegas, NV 89135. Mr. Cloobeck’s principal occupation or employment is serving as managing member of Hospitality Management & Consulting Service, LLC, which is primarily engaged in the business of providing management consulting and oversight services to trusts, not-for-profit associations and other similar entities formed to represent interests of owners of time share resort intervals in the time share industry. Mr. Cloobeck also serves as Chairman of the Board of the Issuer.

Managing Member of Praesumo Partners, LLC

The managing member of Praesumo Partners, LLC is Lowell D. Kraff, a United States citizen. The address of the principal business and/or principal office of Mr. Kraff is 1 N. Wacker Drive, 48th Floor, Chicago, IL 60606. Mr. Kraff’s principal occupation or employment is serving as Executive Chairman of Trivergance LLC, a consulting and advisory firm focusing on identifying deals, structuring transactions, sourcing and securing capital and enhancing value.

The following individuals and entities filed Schedules 13D with the Securities and Exchange Commission with respect to the common stock of the Issuer: (i) Chautauqua Management, LLC and David F. Palmer; (ii) Praesumo Partners, LLC; (iii) Lowell D. Kraff; and (iv) Stephen J. Cloobeck.