EXHIBIT 99.3

                            DEBT CONVERSION AGREEMENT

This Debt Conversion Agreement ("Agreement") is dated January 22, 2005 by and
between Electronic Sensor Technology, L.P., a California limited partnership
(the "Company"), and the undersigned party on the signature page as a "Lender"
("Lender"). This Agreement relates to all loans, promissory notes, advances and
other debt of the Company owed to Lender, included all accrued interest ("EST
Debt").

                                    RECITALS

WHEREAS, Company intends to be acquired ("Acquisition") by Bluestone Ventures,
Inc., a Nevada corporation whose common stock is publicly-traded on the
Over-The-Counter Bulletin Board ("Acquirer"), and to close a subsequent equity
financing transaction to provide capital resources that will facilitate the
Company's R&D, product commercialization, and manufacturing efforts and will
provide liquidity to the Company's equity holders;

WHEREAS, Acquirer has conditioned the Acquisition and Financing upon the
conversion of Lender's and certain other Company debt into Acquirer common stock
and warrants;

WHEREAS, Lender believes that the Acquisition and Financing will provide
significant indirect benefits to the Lender by improving the prospects for the
Company's business and providing greater liquidity of the equity securities
underlying Lender's options.

                                    AGREEMENT

NOW THEREFORE, Lender and the Company do hereby agree as follows:

     1.   Debt Amount. Lender and the Company agree that the aggregate amount of
          the EST Debt is set forth on the signature page.

     2.   Debt Conversion. As of this date, all EST Debt shall be converted into
          the right to receive Acquirer equity securities. Lender shall have the
          right to receive one "Unit" of Acquirer equity securities for every
          two dollars of EST Debt held by Lender. A "Unit" of Acquirer equity
          securities shall equal two shares of Acquirer common stock and a
          warrant to purchase one share of Acquirer common stock at $1.00 per
          share but may only be exercisable if the public trading price is at
          least $1.50. Following such conversion the Company shall have no
          liability to the Lender for any monetary payment, including without
          limitation any loan, promissory note or advance. In addition, the EST
          Debt shall then have no further force or effect and the Lender shall
          no longer have any right to receive any payment from the Company as a
          result of the EST Debt. Under this Agreement, the Lender shall have no
          other rights or remedies other than the right to acquire that number
          of "Units" of Acquirer determined in accordance with the amount of EST
          Debt that Lender holds.


     3.   Miscellaneous. If a copy or counterpart of this Agreement is
          originally executed and such copy or counterpart is thereafter
          transmitted electronically by facsimile or similar device, such
          facsimile document shall for all purposes be treated as if manually
          signed by the party whose facsimile signature appears. This Agreement
          constitutes the entire agreement and supersedes all other prior
          agreements and understandings, both written and oral, among the
          parties, or any of them, with respect to the subject matter hereof.
          This Agreement shall be governed by California law without regard to
          conflict of law principles.

IN WITNESS WHEREOF, the parties hereto have executed this Debt Conversion
Agreement as of the day and year first written above.

LENDER                                     ELECTRONIC SENSOR TECHNOLOGY, L.P., a
                                           California limited partnership

(If Lender is an individual):              By:  AMERASIA TECHNOLOGY, INC.,
                                           Its: General Partner

Lender Name: Edward Staples


/s/ Edward Staples                         By: /s/ Teong Lim
----------------------------------------       ---------------------------------
(sign here)                                    Teong Lim, President

Date:Jan. 24, 2005                         Date: Jan. 22, 2005


----------------------------------------
(If Lender is an entity, such as a
corporation, partnership or LLC)


Lender Name:
            -----------------------------

By:
     ------------------------------------
Name:
     ------------------------------------
Title:
      -----------------------------------


Date:
     ------------------------------------

AGGREGATE EST DEBT
HELD BY LENDER: $399,643.00

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