你也是脑海里因为中国的证书制度（中国还是独一无二的双证制度）而认为证书才是正式的证明。
国外大学的成绩单时非常正式的文件。
在英语国家，记载了学位授予的成绩单，就是学位的最终证明。
现在给你几个证据来帮你科普一下。
首先的事来自于国内知情人对于美国学位的授予的诠释，这来自一个2012年的学位打假的文章，就是那个厦门大学老师的哥伦比亚大学学位的问题:
http://www.guancha.cn/xu-kai-bin/2012_07_25_86746.shtml
文章里面提及到:
"按照美国大学招聘教授的惯例，一旦聘用，都会要求对方提供授予其博士学位的高校封签的成绩单，因为大学成绩单有防伪标志，成绩单由校方放在信封里封签也难
以作假，而且成绩单上会显示所获学位。
如果傅瑾想证明自己的博士学位的真实性，其实非常简单，就是请哥伦比亚大学把封签了的成绩单寄往厦门大学人事处。如果傅瑾真在美国念过博士，她应该知道，
这个手续很简单，每所大学都有网上办理成绩单申请的服务，申请一份成绩单只要10美元左右（加上特快专递10多美元，总共20多美元就够了），2－3个工
作日就可以寄出，1周就可以收到，这也是美国最通行的学位认证办法。"
第二个证据来自英国LSE (London School of Economics)研究生招生网页上对于 “什么才算是学位的官方证明” 的问答页:
https://lfylive.lse.ac.uk/lfy/tc/enquiries/enquiry.html?a=4&q=502&searchString=
What constitutes 'official evidence' of a qualification?
Official proof of qualifications can be in one of the following
forms:
- The return of the proof of degree form properly signed and stamped by your
previous place of study (a copy of this can be found in your Offer
Booklet).
- A certified letter from the academic registrar or other senior
official of your previous university from which you were awarded
your academic qualifications.
-
A final transcript if this states that your degree has been
awarded, the date of award and your final grade.
- A certified copy of your degree certificate. We cannot
return documents so do not send us your original degree
certificate, only a certified copy. A certified copy is
one that has been stamped and signed by an official representative
of your institution, or the British Council or a notary. The
signature should be accompanied by the person's position, name in
block capital letters, and a contact email address.
第三个证据来自于 美国加州大学Santa Cruz分校同样的问答。正式成绩单列在第一个选择:
http://registrar.ucsc.edu/faqs/students/degree-verification.html
Q: I need to show proof of my degree. What are my options? [hide]
A: There are several ways to show proof of your degree:
Official Transcript
A transcript is an official copy of a student’s academic history at
UCSC. A student’s degree is usually posted to their transcript within
six weeks after the end of the quarter in which they applied to
graduate. Order an official transcript from Transcripts Plus.
Unofficial Transcript
If you graduated from UC Santa Cruz since Fall 1986, you can access your unofficial transcripts on MyUCSC. Follow these instructions to print the unofficial transcript.
If you do not know your log in information, contact the ITS HelpDesk at (831) 459-HELP.
Diploma
Diplomas are mailed to the active permanent address between two and
three months after the quarter in which you graduated. Permanent address
may be updated on MyUCSC. The name on your diploma will appear exactly as it does on university records.
Degree Verification
Online verification of degree completion can be accessed through the National Student Clearinghouse. Third parties may be directed to verify degrees through the National Student Clearinghouse.
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